RimWorld does not currently have an official demo on Steam or its website.
Repacks are popular in certain circles because they reduce the download size of the game significantly without removing content. rimworld demo repack
I'll be glad to make changes.
In the gaming world, "repacking" usually refers to taking a game's files and compressing them into a much smaller installer to assist those with limited bandwidth. For a game like RimWorld does not currently have an official demo