In the past, using Flash, I had a game where Santa was flying above some houses (roofs with chimneys). Pressing a key dropped a present, into a chimney if timed correctly by the player. Santa stood still on the screen, while the roof tops with chimneys were moving from left to right.
You can add more game to it, my adding things like the correct package color (or size…) in in the correct chimney. Santa lowers its position after missing a package drop.
An other game I had, was fireworks. Game shooting random flares in the sky. When clicked by user they exploded in nice colors and effects, when missed . No bonus points. etc.
Keep it simple, use ideas from other simple games and add your own ideas to it!
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