Granted Warzone 2100 and the Earth series are not linked however Earth 2160 and Warzone 2100 do share very similar gameplay mechanics, I would have to say that Warzone 2100 is much better (even though much older). There are many annoying parts of Earth 2160; It has horrible sound actors, it has horrible dialogue (both storyline and from units while playing), it has a horrible storyline although to be fair I haven't finished the game as I couldn't really stomach it past finishing the 1st campaign and then starting on the 2nd. It has bad unit pathing, it doesn't have a great unit command interface. The unit design isn't too customisable, it just seems to work on a Rock Paper Scissors method with armour and weapons (3 types of armour/weapons) and then you can add shields or auto-repair but not really designing a unit. It might be a fun RTS to play online but it's certainly not as fun as Warzone 2100.
