Warning Forever is a free game created by Hikoza T. Ohkubo.
The object of the game is simple - fight against an endless parade of ever more powerful bosses. But there's a catch - bosses will change in each game according to your playing style, eventually becoming massive screen filling behemoths. Prefer to destroy a boss from the front? The next boss will come with more front parts. Got killed by a laser? The next boss will come with more lasers, as well as awesomer boss names.


The game has several play modes to choose from: normal play (get more time from clearing stages), 3 and 5 minute time attacks, 3 life play. You can also set your own custom mode. The game saves replays, and also allows you to set your own background music in the game, just copy any .wav or .ogg file into the folder.
This is a good quick way to do some reflex training.
The game is also completely FREE, no hooks attached.
GET THE GAME HERE.
There is an "install", but it is really only a small file extraction.