Four years ago today, American Vice President Dick Cheney demonstrated that friendly fire is turned on in meatspace. No word yet on how Vice President Biden plans to celebrate the anniversary.
Whether to include friendly fire is a powerful factor in games. MMOs tend to exclude it because of the great potential for griefing, while many FPS games keep it. Planetside is the intersection of those two, and I still clearly recall a night when one guy went on a team-killing spree. It took a long time for that TK penalty to build up enough for his allies to be able to fight back without suffering penalties themselves. Take the current WoW AE damage fests in random dungeons and imagine if Blizzard turned on friendly fire for just an hour without telling anyone; would you ever run with a Paladin tank again?
This is the big place where friendly fire becomes relevant: area effect attacks. Games without friendly fire will tend to have more area effect attacks and use them a lot more often.
In City of Villains, a friend’s favorite PvP story remains the time he hit some heroes with AE Sleep and Confuse. Confuse turns on friendly fire. The team’s Defender must not have noticed the Confuse, because he broke the Sleep, hit Fulcrum Shift on the nearest “foe” (thereby debuffing all his friends to boost his damage), and nuked. The Defender was the only survivor of the point-blank, damage-capped nuke. Confuse also makes your buffs affect enemies, so my buddy was also at the damage cap from that Fulcrum Shift. He finished off the Defender in one hit and leapt away with a song in his heart.
D&D 4th Edition has attacks that affect creatures in their AoEs and others that affect enemies in the AE, and you do not want to confuse those two; this point made Fireball the force of nature that it was in 1st and 2nd Editions. Slain by Elf has a story about using an effect that triggers on the death of the nearest enemy to test whether someone was still hostile. The effect did not trigger.
Causing friendly fire is a solid Left 4 Dead Infected tactic, whereas Team Fortress 2 teammates are expected to blast each other with flamethrowers to “spy check.” I like the notion of opening fire on your team and having the bullets hit only traitors. I can only imagine how hugely Spies would need re-balancing without that.
All of this raises the questions of how one defines “friendly” and how the attack knows. Does the attack check against the attacker’s perspective, the target’s intent, or some objective standard of friendliness? Computer games tend to have flags for that, but that just pushes the question back one step to how you choose who gets flagged.
Using the attacker’s perspective seems right, but that brings up issues about how it plays in, which dramatically affects how the power should work. Is the attacker leaving gaps in the fireball (somehow) around targets he wants to miss? If so, does that require additional attack checks to see if he can do it right? Can the gaps be form-fitting, so he can burn tiny targets that are clinging to his friend? Or is it just the will that it not affect certain people, and hopefully your will extends around their equipment and oh my goodness he was holding a baby I didn’t see! It could be the opposite, willing the attack to hit particular targets, but then it should miss invisible targets or ones you are not aware of, which is strange behavior for fire and bullets. Of course, “friendly fire off” is intrinsically strange behavior for fire and bullets.
Can it function on the principle of what your will would be if you were better informed about the situation? That is how Team Fortress 2 flamethrowers work — they do not affect your friends, but that one spy is not your friend, and the flamethrower works on him whether or not you know that (and you would want it to if you did know).
This could be an interesting form of therapy: discover your true feelings from low-damage area-effect attacks! Alternately, depending on how friendly fire works, it could show you how everyone really feels about you.
You usually know who you want dead or not, but single player games include the sudden but inevitable betrayal. You can usually see it coming. This guy is totally going to stab you in the back once you find the ancient artifact. You know it, he knows it, but the game has him flagged not to be affected by friendly fire. It seems that my magic flamethrower has betrayed me too.