I fucking love Phantom Crash and it's the one game I'm holding on to and keeping a working Xbox around for. It feels like no one else played it and it was at Blockbuster for a week, then vanished. The soundtrack is amazing, the setting is fun and interesting, and it has this overall quirky Japanese cyberpunk feel to it that's complemented by a slightly awkward translation.
I think it was released six months too early - the customizable mech arena gameplay seems built for Xbox Live, but it's bafflingly single-player. In a parallel universe, this would be our Mechassault.