Touhou Tougenkyuu: Riverbed Soul Saver

Concerned that the recent influx from The Last Comer and Mystical Power Plant of newcomers to Gensokyo may put the Great Hakurei Barrier under too much stress, Yukari Yakumo has expanded the interior of the barrier into a pocket dimension to delay new arrivals. A massive amount of something is now approaching through the barrier, and bringing a cold front with it. Yukari sends Reimu Hakurei and Marisa Kirisame into the barrier's "Otherworld" to deal with this mysterious invasion before it can endanger Gensokyo.

Résumé

Fan-made Touhou Project game programmed by ido (known for previous fangames The Last Comer and Mystical Power Plant) and Len (known for the fangame Phantasmagoria Trues). The main gameplay mechanic involves a gauge that the player fills up by collecting items. Once full, holding down the bomb key will 'unlock' the player's full strength with a powered-up mode for a short period of time.