Toe Jam & Earl. As a kid, it seemed just endlessly creative, you could just explore & explore forever. And the shit humor - I was the exact right age where every joke was a banger. Although the game itself would be badly dated today, I bet the music holds up well, albeit in short bursts. I still get snippets stuck in my head.
I wanted to play a Mass Effect game, but I suck at cover-shooters. So I put it on easy and ran around punching my way through the game.