TF2 guns? – DinoCap 3 Survivors Review

Why are there TF2 guns in this game? The shot gun, the auto shot gun, flamethrower, RPG, pick axe,and mine launcher are from TF2. I think there are some more but still what the heck are these TF2 weapons doing here?!
Review by Gamestar7400 on DinoCap 3 Survivors.