Tech demos usually showcase specific functionalities based on Circuits, which are not necessarily integrated into a complete Player-Created Game.
Examples from 2019Q2 include: ^FirearmCircuit, etc.
Examples from 2019Q1 include: ^tetrisV3, ^potator, ^funWithRockets , ^StopMotionAnimation, ^SKxMarbleMachine01, etc.
Examples from 2018 include: ^SensoryDeprivation, ^TrainDemo, ^pixelPerfect, ^RacersGizmos, ^vsync, ^AliveGizmos2, ^madBottles, etc.