Use stone to reclaim land and explosions to remove it.
Providing the player with new tools or adjusting the game interface, without fundamentally changing gameplay.
I don't have much experience in the game with biters (I play with a mod that removes aliens and lets you craft the research pack 4, but I believe that biters don't swim, so you can make a moat, and only a small well defended land bridge
I guess you haven't actually used the mod. You can't make a moat with it.
