SONIC JUMP FEVER / Sega / Android
Sonic Jump Fever is reportedly a bite off of the core concept of Doodle Jump, a popular mobile title that I haven't played yet as of this writing. As with other Sonic score-attack-focused mobile title Sonic Dash, even though it isn't the most original idea, it's very well-polished (in this case much more so than the concept it copies) and Sega was wise in copying a control scheme that actually works pretty well within the confines of the Android (espc. when played on a phone).
So, as with Dash, this is a score-attack title that takes you through samey levels repeatedly. Sonic jumps endlessly as the screen auto-scrolls up, and you can also tap for a double-jump. Just grab rings and bonuses, avoid landing on enemies (hitting them from beneath kills them), and try not to fall into the abyss. You'll gradually earn rings that can be used to buy new characters, upgrade existing ones and buy new equippable bonus powers to multiply your score, with the overall goal of tearing up the online leaderboards.
The microtransaction aspect really doesn't get in the way here, serving as a shortcut rather than a necessity, but as with Dash it pretty much destroys the integrity of the leaderboard as the rich kids and the hackers can use their instantly-acquired upgrades and characters to rack scores that a plebian can't possibly match.
Still, if you don't care about the leaderboards, this is a pretty solidly executed little time-filler. It works better for phones than for larger tablets due to all the tilting, however.