Crystal Mines is a great game and probably the best thing you'll find on a baby blue NES cartridge. Mud men run around trying to smear feces on your robot while he tries to collect diamonds. Gather a certain amount and a door will appear so you can move on to the next stage. There's a whole bunch of items and power ups available to keep things interesting thoughout the 100 levels.

Stages 51-100 are mirrored and made harder by different enemies, item placements, and diamond requirements. Move over ROB, CM-205 Mining Robot is here,

There were two spiritual succesors for the NES, one called Joshua and the other Exodus. So if you're into bible games and Boulder Dash these may be for you.

Once I finally learned how to cheat by starting from level 81 I knew I could make it to level 100 in one sitting. Level 97 gave me a hard time as a kid. I eventually discovered the exit on my own. I know it was before I discovered the internet that's for sure, but it's hard to place what age this occured at. I sorta went back and forth with it, playing in small bursts here and there. Come to think of it, Crystal Mines would be perfect for Nintendo Switch cuz it's one of those types of adventures. Do it.