Begin the Slaughter is a timewaster roguelike, designed for ~30 min runs with no metaprogression. You play as a snake-like creature on a world that humans are invading, and you need to slaughter them all.
Each round of the game, you draft a number of building types in a tetrad (tetris-block-like) shape onto the map, and once placed you need to clear a number of regions by destroying the crystals before you gain the ability to play the boss room for that round. 
Placing and completing the boss area presents you with a choice of 2 downgrades, and after choosing one you will 3 more building types. This continues for three rounds. 
Buildings have different requirements for optimal power level; a higher power level spawns more humans, but completed regions with higher power will also produce more upgrades. Upgrades are claimed by placing them into completed regions.
The combat is momentum based: you need to be moving fast enough before you can hurt anyone. Movement tech therefore includes automated wall-bouncing, grabbing the ground to pivot quickly without losing momentum, slithering and the slither-strike, teleporting to above a dead enemy, and launching yourself from a climbing position, in addition to non-combat movement such as wall-climbing and other maneuvers.
The game makes heavy use of a freezeframe technique, (slowing the world down to 10% speed temporarily), to give the player time to process what is happening. 
The demo is currently only the tutorial, which doesn't feature any active enemies. But if you want to get an idea of the movement and movement techs, it's ideal.