MiniGames - Wallball
Preparation - You need Thermal Detonators, Force Push, and a wall (preferably with an open area above it).
Suggested Maps - Bespin FFA as shown in the photos below, and either of the Nar Shadda levels work as well.
It's a challenging game based on the old recess pasttime. Throw a detonator, have it bounce off the wall, and try and push it back against the wall. You might be surprised at how tricky it is.