As salamu aleikum. Is it Haram to play a videogame in which you need to kill the boss and boss drops you an item with a certain chance?

As salamu aleikum wa rahmatullahi wa barakatuh. Is it Haram to play a game in which you need to kill the boss and boss drops you a needing item with a certain chance. Or crates that drops items in certain chances too. Is it considered gambling? When buying crates the only thing you lose is in-game money you have gained. When you kill the boss and don't get the item, you lose nothing but time maybe. I heard it's Haram only if you lose money when doing such stuff