Health Study

In most games, health is the primary or only feedback. After a skirmish you look at your health bar or number and check how good or bad you perfomed. Sometimes you don't come out of a skirmish at all, but that's just another aspect of the feedback system Health.

Generally one can see a game as a black box. You put in your controls(keyboard, joystick, gamepad commands), the game does a lot of things mostly unknown to us, and in the end it provides two types of outputs. It gives you a multitude of indicators, that do provide feedback such as a 3D view or a hit indicator. While theese are a must for playing a game, they generally don't convey the message "you are good" or "you are not good". When you see a red flash on the screen, it usually means, that you were hit by a weapon, but this happens probably a lot, so while you can react to the flash and try to get out of the danger zone, you cannot directly measure your performance with it. The second type of feedback is your health. You can directly measure your performance when looking at your health decrease. The ultimate feedback is to survive or not to survive a combat situation.

A good health system should provide strong and significant feedback and that with little delay. It doesn't do any good realizing that you handled things badly after hours. You'll most likely throw away the game and never touch it again. We want feedback now! If we perform poorly we want to know when we still have the chance to correct it. If the average health loss during a skirmish would be between 2% and 3% of your health, we'd have a hard time figuring out how we perform, so there should be a signifficant decrease if we screw up.

The most primitive approach to a health system violates both requirements. You start a game with a given number of HP and over the course they can only be diminished. You cannot regain Health.

This is a diagram of such a game. You start with 8000 HP. The game designers estimated that you cannot do better than the red area(leave it upwards). Well perhaps you can top that after years of training, but the game's supposed to be played without that. So at the end of the game which might take you perhaps 15 hours you'll surely have less than 3000 HP left. Since a game without challenge would be meaningless, the game designers defined the minimum skill you need to show to be the the border to the blue area. So as long as you stay within the red area, you don't need to improve to finish the game. When you however enter the blue area, you need to improve, because otherwise you're not going to have any HP left at the end. When you enter the green area, you'd need to perform at the maximum estimated performance or better throughout the remainder of the game to survive. If you had that skill, you wouldn't enter the green area, so you're as good as dead. You just don't know it. The violet line shows the path of a bad player. Since he doesn't know how long the game is, he won't realize that it's over bevore he's dead. No he would need to go back many hours to have the chance to correct things. A really bad System, don't you think.

To overcome this problem, the game could be split into several missions. You start each mission with given HP. You either survive, or you don't. I've created another diagram of such a mission that's perhaps 15min long. This mission will be used to compare the different approches later. The allowed health loss will be the same. The only difference will be how you regain health.

The game difficulty should ensure that the player is a bit above the blue curve, which is the least skill required to win, but not too much. If you stay wihtin the red area, you have a chance to survive. If you enter the green area, do a reload. Wait you don't know when you do that :). As earlier you're not expected to be able to do better than the read area. This mission is composed of three major skirmishes(at 5, around 13 and around 21) plus a few single enemies in between. Since the toltal loss when reloading is limited to 15min(the whole mission), this system is better, but the green area is still very large and a rookie player will not recognize when he comes near the green area and has little to no chance to survive the whole.

Health Items, reactivley placed

This is the next system i want to discuss. Now you can regain health by picking up medkits. You also only start the mission with 100 HP and you can't have more than that. Pretty straight forward. The medkits are placed reactively. That means, that any expected loss of Health is made up with medkits afterwards. It looks like this:

I've changed the digram type from area to line. So you can't do better than the red line and you shouldn't be able to do worse than the blue line. But wait you can do that:

Here the player(violet) performs slightly worse than the least allowed skill blue. It takes quite a long time before he realizes this. So this system is not that good either.

Checkpoints

The checkpoint system lets the level designers place checkpoints within a mission. At every checkpoint you are completely healed once.

The checkpoitns are placed at 8, 19 and 25. Notice the dips are a little deeper. This means that if you perform below the minimum skill, you'll die very fast. It's a good system, it forgets all mistakes if you just manage to survive until the next checkpoint. It gives you good response when you drop below the blue line. Yet the 2nd incident around 16 is not quite as challenging as it should be. You shouldn't be able to drop below the blue line and survive.

If you perform slightly worse than required, you'll die in the first and third skirmish. But you'll survive the second. That shouldn't be, but it's still a good system.

Health Items, proactively placed

In this system, the game gives you medkits worth exactly the amount of HP you need to survive the next section. In case you wonder, it gives you 190 HP just like the reactive system did.

Whenever you'd drop below the blue line, you're sure as hell dead soon. All except the first enemy at 2 are potentionally deadly if you perform close to the blue line. In this case i don't need to post the diagram where the player performs slightly worse than the allowed blue line, i think it's pretty obvious what'll happen. I'd say it's a good system.

Constant Regeneration

In this system you regain HP slowly over time even when you're attacked.

Look at this, if played fast it looks almost like the first system, where you cannot regain health. If you perform poorly you'll die much later. It appeals to novice players tough, because a little time can make it forget the most grievous mistakes.

But you can have that with checkpoints too, that don't take away the challenge, and don't force bordom upon you.

Idle Regeneration

In this system you regenerate health when you aren't attaked for a given time.

It's slightly more challenging, just like the checkpoint system, but even more boring than the last.

Fast Idle Regeneration

This system regenerates your health points very fast whenever you're not attacked for a given time.

It makes a joke of single enemies, because you could go get yourself a coffee while killing them without consequences. In the other regeneration systems, this was at least punished with the time waiting for your health to replenish. And the 2nd skirmish around 17 is not nearly challenging.

Applications for Regeneration

Now that i've essentially wrecked the idea of Health Regeneration, i'd like to present two game ideas, that might go well together with health regeneration.

Assume that a game consists of many very small yet potent challenges. You don't go into a full skirmish, because you wouldn't survive that. You pick your targets one or two at a time. Yet the game should be fast paced and there should be a lot of enemies. Think of the amount of medkits required to refill your health after every one or two enemies. It could force you into actively looking for them, wich goes against the idea of a fast paced game. The solution "Fast Idle Regeneration".

Since you only get 35 HP maximum, almost every encounter is a challeng by itself. You don't need to worry about your health over the whole game. You just need to survive the next encounter and everything will be fine, but it keeps you always on your toes.

A second application could be a game like Serious Sam. It throws wave after wave of enemies at you. Assume that the game designers don't want you looking for health, instead want you to fully concentrate on the combat itsself, it could work well with a regeneration system.  You have very little HP, but they regenerate roughly at the rate you're allowed to loose them. When you see you bar dropping you better tune yourself up, because it only forgives small errors and not many of them. Since your health bar fills and empties within seconds, it gives you the highest possible feedback. And it can go on almost forever.

It could work, don't you think!

In the end i must say, that i changed my opinion over the course of my study. I remember really liking regenerating health(like in the original Halo). That's because i don't like to be pushed too hard in games and it gives me the option of doing things my style. My study however showed that you can have a forgiving game also with other health systems, that provide better feedback and enforce the skill constraints a lot better. From this point of view i like the "Proactive Medkits" system the most. In reality the level designer would of course spread the health kits out a little to make the princliple behind the system less noticable.

Critical Damage, is it worth it?

If you ever played an RPG like Diablo or Neverwinter Nights, you've surely seen Weapons with a Critical Hit Chance. So far i've always ignored them, i prefer a more steady damage over a small chance of double or even triple damage. However i always wanted to know, what critical damage actually is about. Was it invented just to have a new feature? What is the exact effect of it? What is it comparable to?

To answer all theese questions i decided to perform some simulations. I usually avoid that wherever possible, because finding an intelligent formula for an effect is much more satisfying and less work. This however is a too complex topic to find a simple formula to approximate the effects. The main problem is, that when you hit an enemy with little HP left and score a critical it doesn't matter because it's dead anyway. There is only dead and alive, you cant kill a monster 1.05 times. This leads to some jagginess in the graphs and in the game itself. When you see them you'll know what i mean.

Anyway first i needed to make some assumptions and simplifications:

• I assumed that you have to face 50 enemies
• Each enemy has 50 HP
• Each enemy does 1 damage(if id did more, it would simply increase the result proportionally)
• Not all 50 enemies can attack you at once, i chose 1 and later 3 concurrent enemies
• Your weapon does 20-30 Damage, you should be able to kill an enemy with 2-3 blows like in most RPGs
• Every attack takes an equal amount of time(yours and the enemies)
• I measure total health loss while defeating theese 50 enemies, because thats what matters in an RPG

Now every Simulation depends on a lot of random numbers, since modern CPUs are quite fast i decided to run every simulation 100000 times and average the outcome. Therefore every run yields the same result up to the 2nd decimal place.

First i did 2 simulations one with no critical chance and one with 12.5% of double damage. Then i tried to find a weapon that performs about as well without criticals as the original weaopn with them. I found this to be 23-33 Damage.

It's pretty obvious that the result will be different for Enemies with different HP. If every enemy had only 20 HP you can always kill it with a sinlge blow, so the extra criticals don't matter. When you kill an enemy with 10000 HP, i'm pretty sure that the weapon with criticals performs exactly 12.5% better. Thats the upper limit, it's not going to perform any better than that. The question is however when does the extra damage kick in. I decided to vary the HP from 20-100 with only 1 enemy attacking at a time:

The x axis shows the health of the enemies. The y axis shows your total health loss while killing 50 of them. The blue curve represents 20-30 damage. The red curve is 20-30 damage with 12.5% chance of double damage. The green one is 23-33 damage. You can see, that the blue weapon results in a higher health loss. The green and the red weapons perform roughly on par. The jagginess is a result of the fact that you can bash an enemy down to -20 HP, but it's no better than gently stroking it to death. It would seem that over the normal HP range 20-30 with 12.5% double damage equals 23-33 damage.

Now one could object and say "usually i'm in a crowd of several enemies all whacking me crazy, your test doesn't cover that". You're right it doesn't, so i did the same simulation and allowed 3 enemies to attack at the same time. You'd be surprised it doesn't matter at all. It simply results in a roughly 3 times higher health loss.

I asked myself however if theese tests are really valid. The red and green weapons seem to perform better at different HP ranges. Assume the enemy has 40HP. You can't kill it in one blow. But with a weapon that deals criticals there is still a small chance to do so. On the other hand an enemy with 80HP requires at least two criticals with a high roll each to kill it in 2 whacks and likey 4 hits. It seems that the additional 3 damage reducing the occurences of needing 4 hits outperforms the the small chance of killing it with 2 hits. So what's in between, what if the enemy has 75 or 77 Hitpoints. Perhaps one of the two weapons is just better at the points i selected but bad otherwise. So i did the same calculation varying the HP between 20 and 99 with a stepsize of 1. Now that did take a lot of time. The result surprised me, though it seems quite logical:

This test only compares 20-30 with criticals to 23-33 damage. Knowing the exact HP of the enemy can make a difference of up to 15%. On average they perform about equal with the latter one beeing ~1% better. Now in a game you either don't know the exact HP of the enemy or you face different enemies and can't take that into account. So it stands that they are about equal.

I did another test to verify that against tougher enemies they perform exactly the same, which i stated earlier. I varied HP between 100 and 500:

Here you see the 20-30 weapon beeing not as good as the 20-30+criticals and the 23-33 weapon. The red and green curve are exactly on top of each other.

As a gamer i'd say "hey i'm facing big and mean enemies and weak cannon fodder at the same time, how does that affect it". There's only one way to find out:

In the first simulation i assigned the enemies random HP between 20 and 100. In the second i assigned them random HP between 20 and 150. In the third simulation i created 50% enemies with 20HP, 30% with 50HP and 20% with 90HP.

The 23-33 weapon performs slightly better than the weapon with criticals. The original weapon is naturally worse.

At the end i can honestly state that 12.5% of double damage equals ~11.5% of damage increase.

What a relief to finally know.....

Replay Value

When does a game have Replay Value? When it provides an alternate path through the campaign? When it has a multiplayer feature? When it makes you wanna play it again after some time?

No, it has Replay Value if at least one additional playthrough is fun. It's a really simple answer. Alternate paths through the main campain, playing as good or evil isn't an indication of replay value.

A year ago i installed Enclave, because i was bored and remembered it to be a good game. Yet i didn't enjoy it the least. When i first played through the game, i didn't notice all the flaws it has and when i did, i excused them and continued playing. But now, that i've consumed the story, now that the graphics are outdated, all that is left is the gameplay experience and it's severly bugged. I could have played every mission as one of several different characters in serveral different ways, and i' like to. But when i actually tried, it only gave me a headache, made me angry about the game. I stopped playing it after an hour, because it wasn't fun anymore. So despite all that it offers it has no real replay value.

On the other hand, i played Half Life several times. It doesn't provide anything new for a second playthrough. But it's the experience, running around in well known corridors, to see if you're up to the job, to do things more elegant. Play it without saving for a whole new experience.

Then there is the game Knights of the old Republic. I played it several times, but never as the bad guy. I just didn't want to.

So what i'm actually saying is that it only matters if it makes you go back, not if it makes you want to go back. And with all that shininess(graphics, story, anxion) gone, all that remains is the gameplay experience.

So when i hear someone saying in a review: "it provides a different path through the campain, you know you can play it as a good guy or a bad guy, there are different endings, etc... so it has a lot of replay value as well" it doesn't tell you anything about replay value at all. Professional reviewers don't have the time to go back and play through the game a second time, just to assess replay value. But when they tell you that they are making professional honest objective reviews, they shouldn't mention what they didn't check, don't you think?

Welcome to the search

For me it's not enough to say "that's a good game" or "thats not a good game". I always want to find out why that is so. I often think about what the causes of the problems in a game are and what could have been possible solutions. What features in a game are not really required for the same experience. Where did it go wrong.

There are so many good games out there, yet no one is perfect. All come with their personal flaws. There is nothing bad about that. A flawed game can still be a good game. But there are always the questions "could it be done even better?", "could the developers forsee theese problems?", "could they have done something about it?", "was it a bad decision that led to the flaws?", "did they sacrifice one feature for another?" and perhaps "were they right to do so?".

First of all i need to clarify what i think is a good game: A good game is fun and addicting. It just means, that the first playthrough is a lot of fun. If the complexity of the game requires you to play an extensive tutorial or restart after 1 or 2 hours to do things right, that should be part of the fun.


In this blog i'll present reviews of games, my theories behind game mechanics and general thoughts about games...

...if you're interested keep on reading.