In CPP, units are very similar to BNW, but more coherent. As a rule, a unit upgrades to something that does the same thing, has the same relative cost, but works better. In every branch, there is at least one new unit every two ages (no more waiting forever for pikemen). Explorers You may think explorers are only worth for first turns, and that cavalry is better to explore mid-game. Now explorers also upgrade to more powerful explorer units. They are capable to stand one hit or two from any unit of its time, so they are worth for exploring any time. Even late game, they upgrade into paratroopers. Explorers gain experience just by discovering new tiles, so if you can keep them alive, they'll make great paratroopers. Their promotions grant faster movement on different terrains, better defence and faster healing, and they may even ignore zone of control. Late game, they may be not so good for recon (mounted units are better), but for infiltration and last blows. Basic melee They are your spearmen, pikemen, so forth. They are cheap, basically cannon fodder, but they stand against mounted and armored units. Their promotions are fine even after gunpowder, so it's worth to keep them alive. The very first unit, the warrior, is gifted against barbarians. Basic ranged They are archers, musketmen, so forth. They attack at 2 tiles range with direct fire (targets obscured by terrain), even with gunpowder upgrades. They cannot take cities and starting from machine gun they get a penalty against cities. Their shots are weak and they are fragile, but provide good support if behind melee units. Expert melee They are swordmen and upgrades. They only exist until gunpowder, when they upgrade into basic melee. Iron is required. They are stronger units that can stand against city shoots and even take cities alone. They offer good cover for ranged units. Siege These machines are the best to break down city defences. Early siege units don't require anything, have a 2 direct fire range and need to spend 1 movement to set up. They start with Cover I promotion. Starting from cannons they require iron. Starting from artillery they have range 3 and indirect fire. Mounted melee These are horsemen, lancers and tanks. They are fast, strong, can move after attack, but aren't so good taking cities. They require horses, and petrol later on. They excel at killing ranged units and raiding. Skirmishers They are mounted archers, cavalry and helicopters. They are fast and can move after attack. They have a range 1 attack, so they are good for hit and run tactics, and are easier to keep alive. Like mounted melee, they require horses, and petrol later.