Although the opening levels may trick you into thinking otherwise, Mercenary Kings is a difficult game. While the gameplay consists of simple run-and-gun tactics, you'll have to think about how to approach every combat situation. You'll find yourself surrounded by enemies, and to make matters worse, some levels have time limits as well. Thankfully, multiplayer makes it much more doable. Up to four people can take part in co-op action, either online or off, and it's a blast. Sure, it can be easy to get lost in the action when everyone's jumping around and shooting, but you'll want to keep enlisting friends to see what the next team will do for you. Unfortunately, there's a bit of repetition. The game will force you to regularly revisit levels, even if you're taking on a whole new mission. There are also occasional bugs that get in the way--particularly with multiplayer match-ups
Speak softly and carry a big gun
Rookies may take a while to get used to the punishing conditions, especially with that clock. Still, Mercenary Kings has a lot to offer for classic shooter fans, whether they're taking matters into their own hands or enlisting a team. It's a charming retro throwback that does the genre proud. 
Expect lots of big bangs
This review is based on the PlayStation 4 version of the game, available for free to PlayStation Plus subscribers. Mercenary Kings is also available now on PC. The game is rated M.