The christmas period has me pretty busy, but I've still managed to make good progress. With all the unexpected rendering power, I've added toon rendering. At the same time I switched to VBOs for rendering so, overall, there's no drop in the number of enemies I can render. Toon rendering simply involves rendering a black outline around the objects, so each object now gets rendered 3 times - once for shadows, once for outline and once for colour.
On the game side, I've added a pickup system now. An enemy, which looks like a bit like a heavy truck, pulls pickups on a trip around the screen. You have to blow up the truck to steal the pickup. If its a carriage, you can attach the carriage by reversing into it. Also implemented is Turret pickups, which you can drag onto a carriage to attach.
Finally, I've done a first pass on an attack wave manager for the survival mode. It basically keeps a database of how many of each enemy type can spawn during an attack wave, and then proceeds to randomly spawn them. Its an accumulative system, so any enemies that aren't spawned in one attack wave, are more likely to get spawned in the next, so the overall spawning of enemies should be about the same per game but the actual positioning and ordering of the spawns will be fairly random.
Here's a shot of the toon rendering in action - taken from the attract mode in the main menu. The actual ingame camera is a lot higher, showing more area to control. I think I'd like to get a few more enemies in place before releasing a gameplay video.