Well, after a couple of unsuccussful ideas i finally have one and have the engine working. The objective will be to kill the people. for now heres a sandbox level: Here

Press number keys to select the types of blocks. Click to place

Placeable

1:Block

2:Sand

3:Water-Slowly drowns guy

4:Lava-kills guy instantly

Other

Steam-formed when water is on top of lava

Obsidian-formed when lava is on top of water

Person-Randomly walks back and forth. Kill him!