OMF:BG= One must fall: Battlegrounds
You can still choose a pilot and 'bot. There's going to be 8 robots in the final game. (beta has 7

)
There are ~50(!) pilots to choose from, which each have strength, endurance, agility, and focus scores. Each pilot has a different background and storyline.
Multiplayer is going to be more of a focus than single player. You can play with 16 players on reasonably good computers, and with up to 64 if you have a furturistic network.
The engine is also supposedly very easy to create mods for, including new robots, weapons and arenas.
BTW, OMF 2097 is freeware now.
edit: Pics weren't working, just go to
http://www.omf.com/ for screenshots. They also have links to reviews with more up-to-date screenshots.