Idea:
1) Switches. Example: you put a switch somewhere at the end, so you must press that switch to open a new way.
2) Gun (something to shoot with) and special weak blocks- with the gun you can shoot weak blocks to make a new way.
That's all for now. The stuff would appear in a side bar which you can see if you pres a button or something like that. There would be special blocks that explode when you press the switch and the switch, the gun would be a item with you start with or it can be picked in the side bar. This would work like: if you pick a gun then, you are not placing blocks, you are placing guns.