With Gates; Back in the day we used to have gates on all 4 corners of each world and you could use it to move units to the other side of the world.
With Relics/Wreckages; Wreckages how they are now but back then they used to hold the relics you see today but they where on your colony not the big ships you can move around, this made a lot of teams fight eachother just so they could have all 10 or 11 in some worlds.
With FarmSystem; With the farm System there use to be a spot where your colony made food and food kept your units a live kept to long outside of your colony or a bracket they'd start dying off. This made the game where you had to play move start when moving and attacking.
ofc some of these things would be need to be fixed before adding them back into the game.