Move with the mouse. Point and click to jump in that direction (jumps need time to recharge, the circle will light green when your jump is at full power). Your jump power recharges quickly when you touch the ground, so wait and bounce instead of clicking madly in the air. Use the physics of the blob to your advantage. Jump up then slam on the ground to bounce higher and recharge your jump at the same time. You can skip some levels and still complete the game, just pause and use the Level Select menu (although this resets your score).