This app was mentioned in 2 comments, with an average of 1.00 upvote
amen man, stair master and playing games on mobile phone during it was a game changer for me in cardio. Broke 175 floors without noticing cause i forgot myself into a phone game (this one https://play.google.com/store/apps/details?id=net.goroid.theend&hl=en_US )