This is a common question regarding unblocked horror games. Baldi's Basics stylized graphics are non-violent in a gory sense; there is no blood or dismemberment. The "horror" is psychological and comes from the tension of the chase and the unexpected jumpscares. Most schools and districts allow the game on their networks via unblocked sites because it is browser-based and does not contain explicit content. However, the game is best suited for older children (middle school and above) who understand the parody nature of the game, as younger children might find the unpredictable teacher genuinely frightening.
Originally created by indie developer Micah McGonigal (Mystman12) for the 2018 Meta Game Jam, Baldi's Basics is a satire of edutainment video games. Players must navigate a schoolhouse, collect notebooks, and solve math problems.