glad it was helpful. After posting I thought of a few other things that maybe of use.
1. C2 executes events top to bottom so organize well. or you may not get the results you expect No "begin step" "step" "end step" "draw step" it's just all one step.
2. draw_gui C2 equivalent is a top most layer with scalerate=0 Parallax=0,0. then placing your GUI objects on said layer.
3 Parent object. is exactly like a Family in C2. But you can only have one object type in a Family. Both can have overlap. GMS Parent objects can themselves have parents. and an object in C2 can exist in many families
4.Sure you noticed by now. you can edit scale and rotate objects on a layout without the fear of everything going to hell. unlike in Rooms.
5. Nothing like surfaces built into C2. some 3rd party plugins give you some of these functions back.
6. Sound in C2 is less buggy then GMS and more responsive in the editor.
7. no "switch" statement in C2. get used to lots of IF statements and use a local variable as your break.
8. you can't store objects as variables in C2. you will need to use a variable as a switch to choose the object instead of directly calling it.
Example, not practical to spawn an enemy each tick but just pointing out the difference.
//step event, or some other event
// create variable. global in this example.
each tick-- Newenemy=choose(1,2,3)
if Newenemy=1 -- system create object obj_enemy1 at layer,X,Y
if Newenemy=2 -- system create object obj_enemy2 at layer,X,Y
if Newenemy=3 -- system create object obj_enemy3 at layer,X,Y
you can see how this could become lengthy if your spawn system was complex.
9. scirra forums don't have a collapsible/expandable code tag. I wish they did <img src="smileys/smiley2.gif" border="0" align="middle" />