Is it gambling?

Assalamu Aleykum Wa Rahmatullahi Wa Barakatuhu is it Haram to open cases(loot boxes) in games without buying them(spending any money real or in game) in game you get free case(loot box) if you play well enough, so i wanted to know, if we are allowed to open this cases or it's still considered Haram (gambling or the random factor or anything else) or in other game you play good you get random reward, to open it you must click a few times, then you will get something random, again is it gambling? im not buying anything, just free gifts, but im worried about the 'chance' of winning something