Instructions in project but more detail here: First click LOVE IT! Move the mouse and the little player slime will follow. Click and drag to draw walls. Slimes can go through these walls, but it slows them down buying you time. There is a limit to how much you can draw. You will notice a bar at the bottom, when depleted you cannot draw, but it regenerates gradually. Changed objective: I realised it would be too easy if it was just over time, you could just keep running neglecting the ability to make walls. So now you can only get points by getting the zombies to eat through walls. With a few levels available, and the ability to create your own, this game is just addictive and will last you a long time.
Thanks to epninja for original project, see below