tldr for short attention span; not enough players = I won't pay for server maintenance costs.
WHY?
Both of my games have been free for a while now, but because the playthrough time for both games is less than 6 hours, there are almost never enough players online simultaneously to warrant spending money, time, and effort to keep the servers up.
Having said that, the developer (me) has been working on an improved graphics engine, which is primarily intended to be used in my third game, however both Super Cube 3D and Polygon Hell will receive an update for this.
After that update (the ETA is 1-2 months from now), the servers will be back online again.
Thank you for your patience and support,
Streetware Games