The Engine that was used to create Half-Life 2 and the 2 coming episodes of the series was nominated as one of the most powerful game engines ever concived for it’s versatility and what it can do.
Reports have shown it can match the Unreal engine easily.
I made a change to a mario game engine. it was pretty cool but i fucked it up bad. the engine turned into a weird fuck up, that made the enemies instead of slapping you and the health bar stuff, they were unrealistic thingys.