Daiku no Gen-san - Ghost Building Company is a Gameboy platformer with some very impressive graphics and a variety of gameplay mechanics.
Despite appearing fairly simple, the game actually requires quite a lot of planning and luck manipulation. For platforming levels, any time you swing your hammer you slow down slightly, so the best movement most of the time is to simply avoid enemies. However some screens require killing all the on screen enemies to advance. In there sections, there is a helpful glitch you might notice where if you turn around just before hitting an enemy, they will recoil in the direction you are facing instead of away from you. The player can get two upgrades, one to improve your hammer and the other a helmet which acts as a free hit. Acquiring the hammer upgrade costs several seconds of animation, so it is not always optimal to pick it up if you are not going to need the extra damage. In the flying levels there are no upgrades and the enemy patterns are fixed, but enemy hit boxes don't spawn immediately and there is a cool down between shots.
Gameplay aside, the Gen-san series is also technically complicated, requiring new tests of mode 3 timing to get console verified. This game also relies on uninitialized memory.
Here is a console verification video:
feos: Judging...
feos: Removed a blank frame at the end of the movie.
fsvgm777: Edited game title to the English one, as it saw an official English release.
feos: Gameplay looks good, but feedback is too mixed to sent it to Moons. Accepting to Vault.
fsvgm777: Processing.