The game was really solid on consoles, but don't forget that there was a portable version, too. If you want to take your quest on the go, try the PSP iteration, which is great with a buddy.
By completing the game once, you unlock the Tesla Cannon and the Spreadgun.
There are also four secret characters to unlock; here's how to get 'em:
|Dante||Finish the game by always making morally-bad choices|
|Isaac Clarke||Finish the game by always making morally-good choices|
|Jonah||Finish the game once on any mode|
|SMILEY||Finish the game once on any mode|