Scirra Construct is an game construction tool that looks like it may be a bit too complex for Primary but if someone could create a wizard interface and some primary school templates and maybe a few LA’s start doing some CPD around it the results could be excellent.
I have 2 gripes and they are obvious: It is a download + install application and the games can not be played in a web browser.
If anyone is currently using game maker you should check this post out on why Construct is better.
It certainly has the wow factor but with alternatives like 2simple’s 2DIY and scratch it may feel like overkill to some!