AO is the first NES release by Second Dimension, and happens to be a puzzle game. It has a dark theme that gives off a dungeon vibe, and the music compliments it very well. The graphics won't strain the hardware, as the layout is just a 2D/top down view.
You control a brick in this 2D world, which is tricky as you really need to think in 3D. The brick takes up 2 spaces when it's laying on its side and 1 space when it's standing up. This is important because you'll need to maneuver through some tricky mazes without falling off of the edge. Don't worry if you do, though, you have unlimited lives!
This game isn't as simple as just getting to the goal, either. It requires you to think about how to interact with switches, weak floors, and teleport blocks, just to name a few. As you progress, the mazes become more difficult, putting your mental prowess to the test.
Another nice feature is that AO is 2 player! You can race a friend to see who can finish all of the mazes first.
If you're into puzzle games, AO will definitely give you more than a few hours of fun!