The screen is a particle count, a row of structures and a clock. Quarks buy the first structure, that structure produces the thing under it, and the thing under it produces particles. A button marked make all buys everything you can afford in one press, which is the button you will end up living on. A stage timer runs from the moment you arrive.
The timer is the game. Resetting the stage trades everything on screen for a multiplier, and the faster you got there the better the multiplier, so every run is an argument about when to stop. Later there are resets that reset the resets, and the structures start feeding each other in ways that make the early rows irrelevant. It is a keyboard game more than a mouse one, plain to look at, and built for people who want the maths rather than the decoration.