Spewer is a puzzle platformer about puking that relies heavily on physics. In this game, you control a little pink blob forced to run a gauntlet of increasingly lethal lab tests.
Spewer is controlled via the keyboard. In addition, you can click and hold the left mouse button to belch a stream of puke, turning the mouse to direct it. Puking downwards can make you jump higher and the puke can fill up otherwise dangerous areas so you can swim safely across. When you're done, you can hold down the Space Bar to suck all your vomit back up, since it can be reused indefinitely.
Levels are short, usually only one screen, and your objective is typically to reach the exit. The levels get progressively harder and as you advance you have to avoid spikes, lava, switches and other obstacles. As you progress, the game introduces different elements such as different areas and types of vomit. The green puke is the starter puke type and let's you propel yourself higher than normal jumping and you can swim in it. The white puke stays in place, even in the air, and let's you move freely inside it. The red puke let's you propel yourself further than the green puke. The black puke stays in place, even in the air, but you cannot swim in it. Instead it acts as solid matter, allowing you step on it. You can use the black puke as stairs or platforms. The yellow puke makes you immune to the effects of acid and lets you swim in it. It also lets you eat and puke acid.
The game includes a level editor for players to create their own levels. The editor creates a code for each level that you can share with other players. Loading a code for someone else's level let's you play through the level that they created.
The game is quite physics-intensive and may be computer intensive. In addition, due to programming of the game, it has plenty of memory leaks and the game often lags more and more as you play. If turning down the graphics in the options doesn't help, the designers have included a link to a downloadable version of the game. However, if you wish to gain Kongregate badges, you need to play the game directly from Kongregate.