Build your base on a platform that warps from planet to planet and escape biters before they overwhelm you.
Large total conversion mods.
Augmented or new ways of transporting materials - belts, inserters, pipes!
New ways to deal with enemies, be it attack or defense.
Changes to enemies or entirely new enemies to deal with.
Map generation and terrain modification.
Changes to power production and distribution.
If you try to "walk" into basement entrance in map view, you will get teleported as if you actually walked through the entrance
This was early issue and is fairly easy to fix, but I kind of liked it, so it is still there (it was useful before mod had home button)