Collect keys to progress.
There are many dangers lurking. You can jump through some walls. Others are impassable.
If you have an older cell phone it shouldn't be a problem. For example, under Settings you can turn off the lighting effects. Then it should also be playable smoothly on older devices.
Take a look at the Developer Info menu item under Info. There is another mini-game hidden there. When you have arrived at the developer information, you can select the icons by double touch (double click).

I will continue to improve the game in the future. So new levels will be added soon.

Hope you like my game.

Greetings Markus