Initially made by a two-student team from the University of Washington using the GameMaker engine, the game was funded through Kickstarter before being released on Microsoft Windows in November 2013.

Players attempt to survive by killing monsters and collecting items that can boost their offensive and defensive abilities.

Risk of Rain Returns, a remake of the game, was released in November 2023 for Windows and Nintendo Switch.

Each character has various statistics and a set of unique moves; for example, the sniper has the ability to hit creatures from a long distance for large, piercing damage but their firing rate is slow, while the commando can do rapid, moderate damage at close range.

There are over 110 items in the game, and these provide benefits such as passive bonuses that improve offensive or defensive capabilities, or a special usable with a cooldown.

The two took inspiration from their favorite games in the past and combined them into a single package, focusing primarily on the platformer and roguelite genres.

[2] The original idea Drummond and Morse had for their game, which they started developing as sophomores, was a tower defense where the difficulty of the attacking creatures would rise with the distance that they were from the defense point, but they found that players would opt to avoid venturing from that point.

[1] They sought to find a means to force the player to keep moving and came to the idea of "difficulty = time" concept.

Drummond and Morse found this created favorable gameplay that created moments of "highs and lows" and keep the player on edge, having times where the player may feel overpowered to the enemies and moments later find themselves in a struggle to stay alive.

[1] Risk of Rain was tested primarily to balance the difficulty system, and Drummon and Morse were aware that with all the available items to collect in the game, it is possible to "break the game" by acquiring specific combinations of item drops which would make the player overpowered or invincible.

This enabled them to hire Chris Christodoulou to compose the game's soundtrack and add several additional gameplay features to the title.

[3] The success of the Kickstarter led to a publishing partnership with Chucklefish, providing them server space and forums for the game's players.

They would later gain help of Matthew Griffin, from Yeti Trunk, another developer that has worked with Chucklefish, to help improve the game's multiplayer code.

[8] In February 2015, Hopoo Games partnered with IndieBox, a monthly subscription box service, to offer a physical release of Risk of Rain.

[9][10] This limited, individually-numbered, collector's edition included a flash-drive with a DRM-free game file, the official soundtrack, an instruction manual, Steam key, and various custom-designed collectible items.