Here's a gameplay video of a very short game where the players didn't get any time extensions. Games can go ~25 minutes in Mercenaries mode. In Survival...
NEW Trailer for version 1.13:
This is a fast-paced cooperative survival map with more of an arcade feel than a gritty/realistic one. The objective is to kill as many enemies as possible to score points before you're evacuated. Kill streaks result in more points. Higher points means higher ranks, better endings, and tougher enemies! Bosses spawn at every 100k points. Each boss kill grants a skill point to all heroes. Minibosses spawn at every 25k points, and additional enemy spawners spawn every 60k points.
There's a mission timer that counts down. Once the timer is up, you'll be evacuated and your score and achievements will be displayed. There are Time Extension powerups at each corner of the map that will extend your mission time by 5 minutes. This lets you get a higher score, but also raises the risk of failure. There's also a survival mode with no timer involved - you just keep going till you wipe out.
Other features -
2 play modes and 4 spawning modes that can be combined for up to 8 different modes of play
86 enemy types including 17 bosses and 21 minibosses
64 different items/powerups
Game difficulty automatically adjusts for the number of players in the game and the players' status
Ability to save your rank and access new innate abilities in future games
10 additional abilities to select based on rank