RTSCraft is a modification for Java Minecraft, which lets you play a real-time strategy wargame directly in the world. You can gather resources, train troops, and attack your enemies.

Wiki

When you spawn in the world, you will immediately be presented with a GUI for team selection. You can escape out of this GUI, or click "Spectate" to look around the map. RTSCraft is best played on pre-made maps, since no modded blocks are required to create terrain ready to play on.

Once you select your teams and everyone is ready, hit start and everyone will be automatically given starting items. The game has begun! Go place your town hall, and build your civilization!