I do have another keys relation suggestion. Currently you use arow keys and enter in menu and WASD keys and space ingame. Why not use the same keys both in menu and in the game. Or even better why not use both in menu. Having the ability to change controls would also be verry good.
As for the mouse cursor do hide the ingame cursor when mouse leaves the game window and show it again when the mouse enters the game window. You do this by using OnMouseEnter and OnMouseLeve events.
Also having the mouse controll in the menu won't be bad.
Why not also include option for multiplayer COOP play. You just need to add another probe for other player and make some level suitable for COOP play, where both players need to cooperate to finish the level. This would definitly make the game much better.
Currently you simly use one power source for powering the teleporter. Why not make the game so that you might even need to use combination of multiple power sources for sucsesfully powering the teleorter. This would definitly come in handy if you decide to do include COOP play.

Theese are my suggestions for now.
I will go and play with the editor some time later today so maybe I'll have even more suggestions later.
I might even try to make a level suitable for COOP play.