While playing a game I found quite a strange word "Hepp". This response is pronounced when you are given money or ammo. I tried to find this word in dictionaries, but my search wasn't successful. I found this word on Duden, but it just says that it's an interjection, and there is no definition at all. I think it might be some encouraging word. If there's the same word in English, could you tell me it?
Since it is an interjection, the meaning of "Hepp" is heavily reliant on the context it is used in. I assume you are "thrown" the weapon or money in the game, and "Hepp!" would be an appropriate thing to say when you are throwing/passing someone an item. The function of the word in this context is to draw attention to the action, as opposed to just throwing something at someone without any words.
Additionally, I have also seen "Hepp!" used as an expression of excertion during a strenuous throwing act. E.g. "The farmer yelled "Hepp!" as he hived the wooden logs on the pyre."
Based on @Asmus's comment below, I decided to update this answer: "Heb!" the imperative of the verb "heben" (i.e. to lift or to heave) is a plausible source of the expression "Hepp!". Based on my experience, "Hepp!" is commonly used to coordinate efforts between multiple people when lifting, catching or holding things.