What Platypus is
Platypus is a fast arcade-style shoot-em-up played as a side-scrolling run through the skies over Collosatropolis. The city has grown until it covers the whole continent: towers everywhere, smoke and poisonous chemicals in the air, and no room left to expand. The Collosotropolan leaders solve this by invading the neighbouring country of Mungola, expecting no real resistance. Mungola's entire defence is one squadron of fighter planes, the old F-27 "Platypus". You fly those planes. The whole game is built around that mismatch: a handful of antique aircraft against an invading battle fleet.
The visuals are claymation, with models and artwork photographed for the game, which gives it a chunky handmade look unusual for a shoot-em-up. It sits in the retro and arcade tradition, so expect straightforward shooting rather than menus full of systems.
Playing it together
Platypus supports two-player simultaneous action, so two of you fly side by side through the same stages and share the screen. That is the co-op setup: both players in the action at once, dealing with the same waves of enemies. The tag list also includes local co-op, and Remote Play Together is available, which lets a friend join over the network as if they were sitting next to you.
Because it is a side-scrolling shooter with dense enemy fire, playing together mostly means covering more of the screen between you and keeping each other alive through the heavier stretches. Unlimited Play means you can keep going back in without running out of attempts.
Before you start
The difficulty is adjustable, so a group can set it to whatever suits them, from a relaxed family session to something tighter. The game is also fully playable singleplayer if only one person is around. Expect a bullet hell flavour: lots of projectiles on screen and quick reactions required, which is exactly what makes the two-player mode work well.
Worth knowing: Platypus Reclayed exists as a separate, reworked version from original creator Anthony Flack and the Claymatic Team, rebuilt from scratch with new models, updated gameplay, new weapons and extra content. This entry is the original Platypus, so pick accordingly if your group wants the classic or the reworked one.