Self-replying to add a couple other classics that aren't already in the thread:

• Penguin Land: A Mr-Driller-like puzzler where you are trying to carefully bring an egg safely to the end of the level - but it can only fall one block distance without breaking. Also, there are polar bears you can crush with boulders.

• Zillion: This game has no business being as good as it is. Side scrolling adventure game where you are tasked with rescuing your captured spy-buddies. You have to loot secret codes from the bodies of fallen enemies, use them to unlock laser doors and progress further into the enemy base. It uses exceptionally large and detailed sprites for the time and is a surprisingly "mature" game for the Era. (Not meaning nudity, just that it is more interesting to someone auth the patience to map out a base and write down secret codes)

Skip the sequel, however. Zillion 2 sucked. a lot.