Thanks for that. I looked at your site the other day, and it's very good - the tutorials are excellent.
I have been planning to make a version of Robotron (what - another one!) but only now - after quite a time playing with DelphiX - am ready to try. I can sympathise with you regarding having time to spend on this kind of thing, and the issues of collaboration and graphics production.

I managed to find a way of doing this already, but modifying the turbopixels unit to get and put to/from different surfaces, and it works just fine. I originally used the original pixels[x,y] but this was horrendously slow. Thankfully, turbopixels is sufficiently faster.
Some exploding sprites (in robotron) can be "exploded" by row (so maybe I can use scanline or something here to save time). I am not using large sprites as I aim to have up to 1000 robots at any one time.

With all of the info I have gathered regarding collision issues (previously my biggest concern) I am looking forward to making some headway with this project at long last!

cheers