Goals

Pro:

• There are blocks with arbitrary shapes.
• They're displayed correctly, with clipping.
• You can't fly through the blocks.
• You can pick the blocks up and move them around.
• You can build things and knock them down.
• There are trains.
• There are interesting curves (the tracks).
• You can control the trains with switches.

Con:

• There is no real physics.
• Blocks have to be convex.

It would be fun to have real physics. I wish I could knock buildings down with a physically correct process, and crash trains into each other, and run them so fast that they'd tip over on the curves. However, I already have enough difficulty understanding 4D blocks without them changing state by themselves. Even the motion of 4D trains on tracks is hard to understand. So, I guess the lack of physics bothers me less now than it used to.