I'd say 2160 if you already finished the 2150 games. The campaign is fun to play (the story is cliche though), more unit customization options, hero units, etc. Like 2150, the campaign includes many different types of missions, such as building up bases, defend important facilities, rescue prisoners, and ofc destroy the enemies. The skirmishes can also be very fun, especially if you can find a friend to play together.
On the other hand, 2140 is less varied in its campaign. Basically all of missions are about killing all your enemies down to the last man. The first few hours may be fun, but then it feels repetitive quite soon. Also, for some reason the AI only works in the DOS version (I guess they turned off the AI in modern version because it makes the game easier). In later missions of DOS version, the game become extremely hard as you have to face 3 or even 4 AI opponents at once, all of them constantly pumping out new troops, and can call off-map reinforcements once their base is attacked. Therefore I find 2140 a lot less enjoyable comparing to the other 2 games.
And in case you want to revisit 2150, in my opinion it has the most immersive campaign due to the way orders are issued to you. It uses a email like system to brief you situations, missions, etc. You also feel more like a commander in a global war as you choose to participate battles in different zones around the world. The pace is a little bit slow but surely fun to play.
Post edited August 28, 2017 by zollac
