I haven't plaid this in years, played it originally on iphone i think Might of played it last on android as it remembers a game i had on a "cloud" save Its so expensive, I remember being able to upgrade easily, i could be wrong as my last save was 6yrs ago but in the old days you would get multiple characters in one pack, thats how you upgrade now it gives you only ONE character and hundreds and thousands of credits just to upgrade ONCE card packs are very expensive both free and paid currency