Happyman guide: If you open the door and he spawns, do not open the next door because he'll prevent you to go in by blocking the door, to deal with it,, you must stay with him until he despawns, since his old mechanic was strict and unfair
If nobody knowns the real title of the game, it's called: "Bad Rooms Game" Which is the similar game to Rooms: Low Detailed, but it has other new entities and only hardcore (May the dev could add Insane mode too) It is an Old Rooms: Low Detailed game. When R:LD was old, it was almost 100% similar to Bad Rooms game.
Also one more thing can do you add old A-250 he was a fast rebounder before and was blue, his spawn was an explosion sound and the sound he made was a fire alarm noise and his second sound when very close sounds like C-45, here is the video link of the entity on how it looked and i guess this is the only video of him..! ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MCmv8aAwUwU.htmlsi=-fsfkImdPm6xn8ap
The old A-27 is rebounds 2.3 times, and the new one is despawning by getting up the roof, and respawning once. This entity once can checking random locker in the latest or previous rooms. Is it recommended to hide only in a table and you can survive him without using any table or locker (only in long rooms).
No raost bc will ask the maker of his videos may need something so I love happyman the old design is sad cuz the angry version of happyman got removed and replaced to new