Wednesday, February 17, 2010

Game Balance Analysis: Battletech 3025 Weapons

I love game balance, and when I study a game, I usually like to look at the game balance and figure out whether the various items in the game are balanced against each other, and which are too powerful or too weak compared to the others. I thought I'd go over my game balance analysis of an actual game.

The game I felt like analyzing was classic Battletech, the version in the 3025 Technical Readout, an old game book I have a great fondness for. I was thinking of Battletech recently, and started thinking of the game balance between the various weapons, so that is what I'm writing about.

I'm not really an expert on Battletech tactics, and it has been quite a while since I've actually played the game. But this is primarily an analysis based on mathematics and logic, supplemented by some play experience, the typical kind of analysis I like to do. And I'm using my old Battletech Rules of Warfare manual for the analysis, not the latest Battletech rules; this is an example of game balance analysis, not a commentary on the current state of the game.

The first thing to note about the weapons is the distinction between energy weapons and ammunition weapons.

1. Energy weapons have unlimited ammunition.
2. Ammunition will explode if it suffers a critical hit; this typically destroys the Mech.
3. Energy weapons are better at clearing woods and starting fires.

In addition to these advantages, energy weapons tend to be smaller but require more heat sinks. Spending tonnage on heat sinks rather than spending the same tonnage on more massive weapons has advantages of its own.

1. If you have a weapon that takes up fewer critical spaces but needs more heat sinks, then more of the mech's critical spaces are filled with heat sinks compared to weapons. This is good, because a hit on a single heat sink is no big deal, much preferrable to a hit on a weapon.
2. Weapons that require more heat sinks are more flexible. If you are in danger of overheating, a mech with heat-heat weapons and lots of heat sinks can just skip a high-heat weapon and cool down a lot. A mech with low-heat weapons and few heat sinks would have to lose a lot of firepower just to cool down a little. This could be important if the mech has taken engine criticals or needs to use jump jets.
3. If you build Mechs like they do in the classic 3025 Technical Readout, with more weapons than heat sinks to handle them, then the flexibility of high-heat weapons becomes really useful. You can choose to fire the high heat weapon, and accept the heat buildup, or not fire it, and cool down.

I should then mention some other important effects I didn't put into the ETR, since I don't feel I can calculate them, but they do factor into my balance considerations. The effectiveness of a weapon is not directly proportional to its damage. Weapons that do a lot of damage to a single area are especially good because they cause damage more unevenly, and can defeat the enemy mech without destroying all armor on all locations. Weapons that cause a smaller amount of damage have the advantage of being more efficient at causing critical hits, since you roll on the critical table for each hit, and the amount of damage doesn't matter. In general, I think the first effect is more important, particularly as the absolute damage gets larger. A 10 damage PPC is definitely more than twice as good as a 5 damage medium laser. And the devastating power of a 20 damage AC/20 is really extraordinarily useful. At damage 5 or less it isn't so clear, and certainly two 1 point weapons would be better than a 2 point weapon. It should also be noted that having two small weapons is slightly better than one weapon with twice the firepower, since one hit can only destroy one weapon, and you can choose to fire only one for heat purposes.

To analyze the weapons more conveniently, I'm going to make up a number that estimates how resource-intensive the weapon is. It will be the tonnage of the weapon, plus 90% of the heat, plus the weight of 15 shots of ammo. This total will then be increased by 5% for an ammo-based weapon (to account for the disadvantages). The numbers don't have to be super-exact, since I'm not interested in perfect balance calculations, only determining whether different weapons seem close enough that you could argue over which one is better.

I made some charts calculating the ETR, damage, and damage efficiency of each weapon. The tables didn't copy easily into the blog, you can see the version of this article with tables here.

Let's start out by examining the long-range weapons. They generally have a range band of 5, or 6 with minimum range 3, or 7 with minimum range 6. It is hard for me to make a statement on whether the longer ranges with higher minimum ranges are better or worse, so I'm just going to treat them as pretty close.

My baseline weapons are the PPC and the laser laser. These weapons are pretty similar to one another.

The AC/10 seems like a pretty similar ammunition-based weapon to these two. By my estimate, it is pretty close, just about as good as the other two. The ETR is very close to that of the PPC, which does the same damage with slightly different range characteristics. I'd prefer the PPC, but still, they are pretty close.

The AC/5 is clearly an inferior weapon compared to the PPC. It is significantly less efficient than the PPC in my calculations, and it does less concentrated damage. Even if you ignore the advantages of the PPC as a concentrated-damage heat-based energy weapon, and use a more favorable way to calculate ETR, you still have the fact that the AC/5 does half the damage of a PPC, yet consumes more than half the tonnage.

The AC/2, on the other hand, is just silly and useless. It requires about 75% of the resources of the AC/5, but does 40% of the damage. It does have the best range characteristics of any weapon, but the extra range is not worth this much! And the AC/5 is already a weak weapon to compare to. It is true that it has the very longest range in the game, so maybe you could use it for some sort of strategic siege. But the weapon is so weak that if you carry the standard amount of ammo for mechs in the 3025 readout, you won't be able to seriously hurt another mech at long range before exhausting your ammunition.

The LRM/5 feels a bit weak to me. While its damage/ETR is slightly higher than average, the damage is very non-concentrated. And although the range is very good, I feel the terrible accuracy at close range is a real hindrance. However, that being said, for balance purposes it is close enough to the PPC and large laser that I would consider it an equivalent weapon, one you could easily argue was as good or better.

The other LRM's are practically just scaled-up versions of the LRM/5. They use slightly more tonnage and fewer heat sinks, and cause slightly more concentrated damage. I consider the LRM/5 the best, but really they are so close it doesn't matter much.

Next, we move on to the short-range weapons, those with a range band of 3. They are easy to compare with each other, but hard to compare with the long-range weapons, because I can't say for certain how much better the longer range actually is.

My general feeling is that the SRM/6 is the weapon closest to being balanced with the PPC and Large Laser. It has slightly more than 50% more damage efficiency, which seems to be in the ballpark of being an equal exchange for the long range.

The SRM/4 and SRM/2 are just inferior versions of the SRM/6. This can be seen pretty clearly by the fact that the heat output is more per missile in the smaller launchers, while everything else scales about evenly. This assumes you aren't using the optional Inferno SRM/2 rules; that weapon is insanely potent for its size.

The medium laser has a much better ETR than the SRM/6, and seems like an extremely efficient weapon. This has always been my intuitive feel as well; the key is that the one ton weight is just amazingly low for a weapon with pretty good damage. I tend to think that the medium laser is more efficient than any of the long-range weapons, despite the shorter range.

The AC/20 is a queer weapon. The ETR is pretty low, rather less than the SRM/6. But the damage from this weapon is so amazingly concentrated, it is absolutely deadly. 20 points to one hit location is just incredibly frightening. Because of this, the power of the weapon is hard to judge. My feeling is that it is a very good weapon, much better than an SRM/6, but it is probably not as efficient as the medium laser.

Finally, the point blank weapons. Again, it is hard to say how these compare with longer-ranged weapons. The Mechs in the 3025 Readout carry so few of these that it is almost irrelevant how efficient they are, they just don't have much effect on the total effectiveness of the Mech. But when you use the Mech creation rules to design your own Mech, it is very tempting to load it with an enormous number of point blank weapons.

The small laser is what I would think of as the "standard" point blank weapon, although with so few point blank weapons, this isn't a very meaningful designation. If you look at my ETR, I estimate it is more than 50% more efficient than the medium laser. It seems plausible that 50% might be worth the extra range of the medium laser, so these weapons seem maybe equally efficient to me. Since the medium laser is unusually good, I would say the small laser is awfully good too.

However, if the small laser is good, then the machine gun is really good, at least according to my ETR. It has the big disadvantage that the tonnage I'm calculating doesn't "come" with a heat sink; most of the tonnage of a small laser is in the heat sink, which can be used for another purpose if you are out of range, but the machine gun just sits there taking up space if you don't get to point blank range. But if you are building a custom mech, the machine gun seems like the best weapon in the game. You can get 10 machine guns and a ton of ammo for only 6 tons!

Now, there are some caveats to this. Saying it is the best weapon in the game doesn't necessarily mean you would actually want an army of nothing but machine gun mechs; there might be some situations they can't handle. It just means that in a typical Mech battle, if you could replace one of the Mechs with a custom design, I'd guess you couldn't do better than to put on a horde of machine guns.

Another point to note is that some of the weapons are much less effective when used in the typical configuration of a mech in the 3025 readout. You can make a pretty evil mech with machine guns using the mech creation rules, but machine guns on the standard mechs are usually pretty awful. They often have 2 machine guns with a whole ton of ammo, which is way too much ammo. And the key to counteracting the poor range of a machine gun is to be totally focussed on getting to point blank range. With so few machine guns, the average 3025 Mech may have little incentive to close the distance, so the machine guns stay idle, and might better be replaced by a different weapon.

The final weapon is the flamer. Since a flamer is identical to a medium laser, except that it does 2 damage instead of 5, it is clearly worthless for any purpose other than setting fires. In my opinion, it is pretty worthless even for that purpose. I would rather have a medium laser to start fires with. Even though it has only 7/12 the chance to start a fire, it can start a fire from three times the range. The flamer is mostly good if you want to set your own position on fire!

A final note is that from a strategic point of view, energy weapons are clearly better than ammunition weapons. The odd thing is that, in general, they do not seem to pay anything for this ability. The average energy weapon is about as good as one of the better ammunition weapons, even without the extra advantages of being an energy weapon. I'm not sure why you would mess around with the logistics for ammunition when energy weapon based Mechs are at least as powerful and never need rearming.