Press SPACE to buy a standard robot (at the cost of 5 points).

Each of these produces 1 points per second. 

Press ENTER to buy an advanced robot (at the cost of 250 points).

Each of these produces 75 points per second. 

Press ; to buy a super robot (at the cost of 1000 points).

Each of these produces 250 points per second. 

Press - to buy a mega robot (at the cost of 1000 points).

Each of these produces 1,350 points per second. 

There is no limit to how many robots you can have. 

(At some point they go off the screen but you still lose money and gain money/second).