I know you from the sand art thingy (not related to the idea)
So heres the games (2 options, or both)
Game 1:
Chess Defense
You have to protect the king (black or white its optional) by placing the chess pieces around the king. The enemies (opposite of your color) will attack you.
This game is infinite
Currency's Tyers
Game 2:
Airfry a Taco Shell tycoon
- There's the local taco shop producing tacos, but theres the machine that gets the filler out to the tortilla (on a conveyor)
- And theres the eletricity thing (potrayed as a ball) going through the wires to the airfryer
-You can decorate the interior
The game currency is Tacés