東方斑桜 (Touhou Ikaruga) - Madness 1cc + TLB - 3.2 Billion

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Now in glorious 60 fps.

東方斑桜 otherwise known as Touhou Ikaruga, Touhou Madara Sakura (or Touhou Trails of Sakura, if you want to try romanticizing it) is a Touhou fangame produced by 幽々燦々. I personally like to call it Yuyukaruga.
The game is obviously a homage to Ikaruga and you can see a ton of references to that game in the mechanics, level design and the music.

The polarity mechanics work exactly the same as in Ikaruga. You can absorb blue bullets when you're blue and you can absorb purple bullets when you're purple. You do more damage to an enemy when you're the opposite color of it and you also have homing lasers and enemy lasers that push you around.

The scoring system works completely different however. In order to get the most cherry and points from enemies you have to kill them with the same color shot. Killing them with homing lasers of the same color gives you even more.

There is no chaining or anything like that but speedkilling enemies is still important as it makes more enemies and enemy waves appear.
The way bosses work is that you get more score the faster you kill them. Besides that you also face a Last Word when you meet a certain score requirement . Failing a Last Word doesn't make you lose a life. The final boss does not have a Last Word.

Besides absorbing bullets, picking up dropped cherry also charges your homing lasers. Since you get more cherry from killing enemies with an attack of the same color, you get a particular balancing act. If you don't get enough cherry you also don't get enough lasers to produce more cherry, and thus more chances to use lasers.

This is the highest known score at the time of upload.

Official website:
http://yuyusansan.wpblog.jp/