@OP

.....SOLD!

The X version is the result of some weird program (called the X program) thats used on some digimons and they turn out stronger (it was featured on a movie that i didnt bothered to watch),  and the reason why i know this is because in Digimon World 4 (on the PS2) you actually can evolve to it (although i was never capable because of some crazy requirements) and the intro trailer that plays at the begining of the game shows bits of the movie (and you see wargreymon X there), so it seems that the game was some sort of sequel to said movie.

also on a side note Digimon World 4 was a action game where you actually played as the digimon, and you can equip different weapons form swords hammers to special claws etc... it was actually really fun but the CRAZY requirements to evolve to some digimons was the worst part of the game, heres a screen of Wargreymon X on the game, (yeah its really low resolution but its hard to find a decent image of that game.).

you still have the game!, wow i wish i even had my PS2 but it died a looong time ago.