Madness: Project Nexus will stir nostalgia for people who used to play browser games via Newgrounds. It's a fully 3D entry in the Madness Combat series of Flash animations which began in 2002, and named after the Flash game released in 2012.
The Madness series was peak Newgrounds, with extreme violence, basic animation and just as basic humour. To give you a very quick sense of its tone: one of its antagonists is Jesus.
Madness: Project Nexus is at least more polished. It's a run 'n' gun brawler, playable in co-op, in which you smash through arenas by fighting giants, assassins and government agents using melee attacks and many, many weapons.
There's a story campaign you can play with up to three people, in which you "infiltrate heavily guarded installations, survive cultist-ridden tunnel networks, fight back against dynamite-wielding cannibal bandits, and dodge the grasp of armor-plated Mag Agents over three times your size." There's also an arena mode where you can create your own character, "advance through specialized skill tiers" and build your own custom weapons, according to the Steam page.
I don't personally have nostalgia for that era of the internet where everyone discovered Adobe Flash the same year they first saw The Matrix, but I do like co-op shooters. There's also, I have to admit, a pleasing upward trajectory from a my-first-animation.flv equivalent in 2002 to the scale and variety on display in the video above.
Madness: Project Nexus is available from Steam with a 10% launch discount for £17.54/€18.89.