Build, then fight from inside it
Block Fortress 2 mixes block building, tower defense, and first- or third-person shooting. You pick a planet, build a fortress out of walls, turrets, traps, and more than 200 block types, then step into the fight yourself to hold it against waves of enemies. There are four enemy races to defend against, and the world adds pressure on top of that with a day and night cycle, severe weather, lava, acid, alien monsters, and other hazards. Your loadout matters as much as your layout: dozens of weapons and items are on offer, including a rocket launcher, mini-gun, plasma rifle, and a jet pack, plus an army of specialized soldiers you deploy to fight alongside you. Ten planet biomes each bring their own dangers, and you get a command ship to build a home on between runs.
Playing with friends
Online co-op lets you team up instead of holding the line alone. You can play the campaign together, run missions, and build in sandbox mode as a group. Building is open-ended, so you and a friend can split the work — one laying out walls and turrets while the other sets up troops and gear — or just build a towering fortress or sprawling castle however you both feel like. The same freedom applies to the mission builder: set up massive battles, stealth missions, obstacle courses, or giant worlds, then share them and download what other people have made.
Before you start
Expect a mix of planning and shooting rather than pure tower defense. You place the defenses, but you also pick a weapon and join the combat directly, so your aim and movement count alongside your base design. The environment is not passive — weather, lava, acid, and monsters will pressure the fortress no matter how well it is built. Missions and sandbox give you room to experiment before survival mode throws everything at you, and the level editor means there is always something new to load up when you want a break from the campaign.