If anybody experiences the problem with the crates sliding of the conveyor belt, it would be very helpful if you could write on which level it happens. Thanks.
Hey guys, thanks for the comments though not all were exactly great :-)
I haven't done this in Unity to be cool =) it's done in Unity because this platform supports C# which is my preferred programming language. I do not know Flash/Flex/Actionscript, so it was not an option for me. No doubt this game could be done in Flash though.
The timings for the levels has been hard for me to get right. Make them too long and it's too easy, make it too short and it's too difficult. After working on the game for quite a while, it also gets hard to look at the difficulty level objectively. I'll probably increase the timings on most of the levels based on the feedback here.
Drak0n's comment about crates moving off the belt: Yeah this is a real annoying bug, it has appeared several times during development, I thought it was gone but here it is again :-) I'll have another look at trying to fix it while also redoing the timings.
Thanks for all the plays in any case!