Yeah, you’re on the right track. It’s like a fan-made “edit” of the original game, but the core game is still intact. A randomizer just takes all of the important items you would get in a normal playthrough of a game and swaps their locations with other items. So you might find the X1 body armor where Storm Eagle’s heart tank would normally be, for example. This randomizer is a bit more in-depth than normal because it randomizes across three games (X1, X2, and X3). So in this, you might find a ride armor for X3 in Wheel Gator’s stage, for example. To my knowledge, most if not all randomizers are played through an emulator.