Temple of Spikes is a self-described "hardcore" 2D platformer about exploring a jungle temple which, you may have deduced, is filled with spikes. It's also filled with spiky bosses, priceless treasures, and fireballs. Also Cthulhu, provided you select him from the game's 25 playable characters, all of which have unique abilities according to developer Tigrido Inc.
Aside from its huge cast of characters, Temple of Spikes' main hook is the ability to control time—more specifically, the ability to rewind time Prince of Persia-style when you die, and to slow time to avoid dying in the first place. It also supports up to four-player local co-op.
Tigrido says Temple of Spikes sports 30 levels worth 50 hours of exploration, to say nothing of an optional speedrunner mode. It's out today on Steam for $10.
Oh, and if you absolutely have to have more difficult, co-op 2D platformers with spikes in the name, I'd recommend the criminally underrated 1001 Spikes.