X is a near perfect platformer. It moves along with an absolutely astounding soundtrack, phenomenal theming, and progression-based upgrades driving the game. The weapons all feel fun and useful, which is something the classic series really struggled with on the NES.

X is a game all about improving, and the player growing alongside X feels so fluid and natural that it's hard to beat. Sigma is difficult final boss that leads to the kind of catharsis you can only get from games like this once you finally get that last hit in. My only change would be to have the dash be default.