the theme is so hard i can't make any game with it
Then ask Chat GPT, that could help you
Think what can be turned off and on. Like some electrical appliances
Try something like the on/off block from the Mario series.
In my game, it is on/off the fan that creates a dust monster
What if you think more generally, like jumping on and off a platform or on and off a horse/boat/train, lots of things.
thats nothing about it