This is an overly simplistic shooting game. In co-op you, and up to three team mates fend off waves of attacking aircraft. Since there is no communication options between players, you will need to watch your gauges carefully to repair your ship, which will likely result in duplication of effort.
In a sense, this is a little like Beach Front, with no urgency as you can always repair your ship. Please be aware that this is NOT Guns of Icarus ONLINE.