I just watched the showcase on YouTube, it was great, thanks for doing it and Octojam. Now I'm watching the other showcase videos in reverse order. I'll address a few things from the video about Dodge Catch Shoot.
The ability to move up is currently pointless. But I'm glad you found it :)
The player is drawn in an XOR fashion, but the falling objects are each erased and redrawn individually. I use the redraw of the objects to determine collision with the player. I thought about switching those around too late, so I'm saving it for the next version.
The laser is the only thing using the delay timer (during gameplay), it's used to make sure the laser remains on the screen long enough to be seen. The falling rocks and player movement each have their own timer values. All three timers are balanced for 500 cycles/frame. I haven't tried adjusting the timers for a lower cycle speed. It's too complicated and a good reason for a next version.
The "E" in the upper-left is the error screen, there is a bug I haven't tried to fix yet. The player is allowed to move faster than the falling rocks, so the ship can move into a falling object and not be detected immediately. If a fire command is processed before the rocks are moved down (and collision detected) the program is unable to locate the object the laser hit and shows the error screen.
I plan to start over and use XO-Chip instructions for version 2. I'm excited to have color and sound.