SCP Nickname: Lucent Beams
Ingame mechanics: This guy could work as a randomly occurring hostile SCP that'll manifest on a wall, perhaps disguising itself as a beam of light, which could be done with some sprites. However, it should only spawn if or after the player has come across it's containment chamber, which is described as:
If it chases you, and comes within close enough contact, it'll give you a light zap, which won't hurt you too much, or kill you instantly, but rather has the damage of a single bullet to your leg. Like 106, you'd have to outrun it for it to lose interest.An ellipsoidal room with a uniformly-reflective interior, such as nickel or chromium plating. The atmosphere in the room must be maintained at a temperature of between 260 and 307 K, at a relative humidity of 50% or less.
The confinement chamber must be equipped with a light-tight airlock fitting equipped with an electronic interlock to prevent both doors from being simultaneously opened. Though SCP-640 is not known to be able to assume a gaseous form, these doors should be airtight and, if possible, watertight to facilitate emergency containment measures.
Artwork/Models (optional): A screenshot edited to perhaps show how 640 could be waiting for prey in a room.
Spoiler