NPCs are in many games the foundation on which it operates. NPCs create the illusion of inhabitants or assign purpose to the player. Whatever they do, they represent characters. Introducing a character has a certain margin of error, as a poorly portrayed character may cause more damage than the NPC would add. Without creating a believable environment which would include the NPCs, immersion could be difficult. As such this thesis investigates the effect of different behaviours to NPCs. With the focus on how visual and logical behaviours affect the players’ perception of their believability. The experiment was conducted in a game of the RTS survival genre. With the visual behaviours selected from the games Banished[1] and Frostpunk [2] the logical behaviours were inspired by F.E.A.R [3]. In the experiment testers were used to test three versions of the artifact. The first acted as a default and was used as the starting point for the second version which introduced enhanced visual behaviours. The third continued and added a predictive functionality as logical behaviour. The tests concluded that the visual behaviours had a positive effect on perception but no conclusive evidence to suggest the logical behaviour had the same effect.