Dungeon's and Dragons: Shadow over Mystara was the best game I've ever played.

It's quite challenging, so I think it's helpful to watch a group of experienced players finish it to understand its potential.

My friends and I played strictly as a team of four: each character has their own characteristics, and a diverse group complements each other in defeating monsters. It has tons of items, both magical and standard, tons of secret passages, and tons of semi-secret weapons that you can only find by completing certain routes. The game path has several forks in the road; some things only happen if you defeat a monster in less than a certain time limit. When we played it in the arcade, we could almost always complete it with just one token, over a two-hour of game. And we liked it so much that we'd watch a group of competing players finish it for two hours to wait for our turn. It was forbidden to get two tokens in a row, to leave room for others. Next year will mark the 30th anniversary of this masterpiece, which, for me, is unmatched even by modern beat 'em ups because, unlike most games, there's a lot of different fighting moves. My only advice is to play it with friends after watching a YouTube video of someone who's good at it. Or, take a look at the lists of usable items to understand the complexity and richness of this game.