A Truegamer is someone who spends a significant portion of his time playing computer games, whether on a games console (PS3, XBOX etc) or on a PC. Likewise, a Truegamer spends a large amount of his income on computer games and related stuff (hardware, peripherals etc). Most of all, a Truegamer NEVER cheats in an online multiplayer setting. Once you do that, you give up your status as a Truegamer, for good.
Anyone who uses an aimbot, a wallhack, or uses any other kind of cheat to win against opponents in an online multiplayer setting, is not a Truegamer.