So the RNG is so brutal in this game and it is in everything that will end up being bad so instead of giving 0 event cases to players who played 10 h and give 4 cases to players who played 2 h, make that everything goes by time played, for example, for each hours played you will be awarded with 1 cobalt, or with 1 limited event case, so for example, each 15 min, or 10 min, you will get a lead card, each 20 min, an iron, each 60 or 45 min, 1 bronze, each 3 h or 2 h and 30 min, 1 silver, each 5 h or 6 a gold, and each 10 h a cobalt
Probably the hours that you will spend for 1 cobalt arent enough, so make it like each 50 h 1 cobalt, but you probably got the idea
