AddPromoItem() / AddPromoItems() are restricted versions of GrantPromoItems(). Instead of
scanning for all eligible promotional items, the check is restricted to a single item
definition or set of item definitions. This can be useful if your game has custom UI for
showing a specific promo item to the user.
public static bool AddPromoItem(out SteamInventoryResult_t pResultHandle, SteamItemDef_t itemDef) { InteropHelp.TestIfAvailableGameServer(); return NativeMethods.ISteamGameServerInventory_AddPromoItem(out pResultHandle, itemDef); }