The First 15 Minutes of Downwell (Vita)

Copied from MobyGames:Downwell is a vertically oriented action game about a boy who goes down a well looking for treasure. It consists of twelve levels, and the environments are randomized for each session with a final boss at the end.Firing is only possible in a downwards direction. The boy wears gunboots that have a limited amount of charges, recharged by touching a solid surface. At the same time each blast provides a slight upwards push. Destroyed enemies leave behind gems. By collecting many in succession "gem high" is activated, making the weapon more powerful for a short while. Also, combos is a way to recover health.The boy only has a limited amount of health and when he dies the entire game needs to be replayed. Every level has a few platforms with a time bubble where time stands still when the boy is inside. These bubbles usually lead to side areas that contain treasure caves or shops also randomized every time. After completing a level a bonus or a perk can be chosen from a randomized selection, such as better range and accuracy, more upgrades and HP, a jetpack, a drone, causing dead bodies to explode etc.

http://www.nicovideo.jp/watch/sm42610560