I picked up Earthfall at the discounted price on Steam and I'm glad I did. The game is a charming "love letter" to the Left for Dead games IMO.
If you loved the LFD series, you'll like this game. The game is a solid fps using Unreal Engine 4. It's a 4 player action/shooter
game where Earth has been invaded by nasty aliens and you along with your friends battle across maps to get to the objectives.
You can play campaign missions via solo(with bots) or multiplayer, "Invader/horde" mode solo(3 other bots play with you ala LFD) or multiplayer, can make your own games to play online, etc.
The PC version is still on sale today via Steam for 70% off(think it ends sometime today so hurry!) at $8.99 with the deluxe version setting you back $11.99.
While the online player base isn't huge, it seems to be a sizeable, nice group of dedicated fans(many I assume LFD veterans) and the Steam forum for the game
is active for players wanting to add others.
Perhaps we can organize a NeoGAF group for Earthfall here if one doesn't exist already?
The game is available on PC, Xbox and PS4.