Space Shooter - 2d vertical schmup that is far too hard and the interesting mechanic is far too easy to miss. Destroy enemies and collect their shapes to add more bullets and shields to your ship. An implementation of a game I heard about 20 years ago written in java that had you collect the husks of defeated ships to add them to your own.
Block Breaker - Arkanoid clone where I played with the ascetic to invoke a synthwave feel. The speed of the ball increases with time so the level gets harder the longer you play. Rewards accuracy out of the gate.