Also try to have as much diversity as possible. This is one of my favorite quotes: "This game is so imbalanced so that it get balanced".
* nerfed movement for white pieces to balance out first-move advantage
* added "undo" and "knight blast radius damage" DLCAre you thinking of any particular examples? First to my mind was Starcraft 2, which gets regular balance patches. And community bitching because the patches take to long/don't conform to everybody's pet theories/...
We all hate changes. Look for things that annoy ppl and try to fix those problems. Try to add new content, instead of changing old mechanics. This should be done slowly though, to give the mediate players a chance to get a hang of it. In a player vs player environment, it can take years for strategies to settle in, and for the majority of players to adapt.
That is embodied by the board game Cosmic Encounter.
It is a sci-fi negotiation game of space conquest. It has tons of special powers that effectivelly bend or break the rules. Some powers are so over-powered that the other players end up ganging up / never helping the OP player. (The game is best played with 5 players)
There are downsides to the design: one, it's hostile to new players who don't have enough knowledge of the game (this is true of any skill based multiplayer game, but in games like CE the effect of an unskilled player on the game can be profoundly wonky). The other issue I have is that players with a weak initial position have to win through negotiations, and so have fewer paths to victory than the players in powerful initial positions. I rarely ever see the "weak" player win in Cosmic Encounter (whereas the moderately-powerful and very-powerful players seem to have about equal chance at winning if they're playing competently).