So, good games for 2 or more players, online/same console/LAN. By this I mean fair, balanced, even etc. Where unfair advantages cannot be abused.
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I vote for Super Smash Brothers Melee and Brawl as the best. Every character is perfectly balanced(low speed-high power, then vice versa). There are no un-lockable items you need to spend hours playing to get that completely messes up the balance of play. And especially no unlock able character decorations. You can pick levels easily and each player gets the same percentage of damage/advantages from it, or whether you get affected at all. And Brawl has lag-free online multiplayer too.
You could also argue about HL2 Deathmatch being balanced, seeing how the weapons are based around finding them around the map, but the design in general is pretty obsolete. Still, the levels can be really cool (dm_runoff ftw).
Team Fortress 2 used to be cool. But the new item and hat system changes have completely ruined the gameplay. New weapon releases cause everyone to try and get them, which then sets a complete dominance on the new item owners until everyone either gets that item or learns how to take advantage over its downside. The Amputator is a good example. The taunt gives your team mates 75 health from a distance, and there is no limit on how many times you can taunt. Oh, and it has no downsides. Period.
The Left4Dead versus mode is decent, but it got even more unbalanced for its sequel. Special infected tactics can overtake even the best of Survivors, such as Spitting at a downed player.
So, what do you think? What multiplayer game is the most balanced?