I found the problem. I built circuslinux first. Then I used that build script as a template to build monsterz since they are built pretty much the same way. I missed a change to the script. So it created a monsterz menu entry named circuslinux.desktop.
I bet you installed circuslinux first, then monsterz.
The circuslinux installed correctly. Monsterz replaced the good circuslinux.desktop with a monsterz one posing as circuslinux.desktop. But visually would look like a monsterz.desktop. Okay, that confused the heck out of me. lol
Here's a quick fix for you and whoever installed these. I will fix the monsterz package.
To restore Circus Linux.
cat > /usr/share/applications/circuslinux.desktop << EOF
Comment=Circus Atari Clone
To create the REAL Monsterz menu entry.
cat > /usr/share/applications/monsterz.desktop << EOF
GenericName=Monsterz Puzzle Game
Comment=Puzzle game, similar to Bejeweled or Zookeeper
I'm very sorry about that! I'll fix it right away.