Slay.one is described as '"Slay.one" is a free multiplayer top-down shooter which you can play directly in your browser - no install required! Features the game modes Deathmatch, Team Deathmatch, Ranked, Zombie Deathmatch, & Capture the Flag!'. There are six games similar to Slay.one for a variety of platforms, including Online / Web-based, Android, iPhone, Mac and Windows. The best alternative is surviv.io, which is free. Other Slay.one like games are Enter the Gungeon (Paid), Vertix Online (Free), Utilizer Deluxe (Free) and Demon of Justice (Paid).
Enter the Gungeon is a bullet hell dungeon crawler following a band of misfits seeking to shoot, loot, dodge roll and table-flip their way to personal absolution by reaching the legendary Gungeon’s ultimate treasure: the gun that can kill the past.
Utilizer Deluxe is a mobile arcade space shooter mixed with a match 3 genre! Utilize fancy space monsters, fight with dangerous bosses, make color blocks combinations, upgrade your spaceship, complete all sectors and test your skills in the survival mode!