One of the few Touhou games worth playing, maybe even buying if it's not impossible to get it outside of Japan.
I downloaded it here (Chinese site) http://u.115.com/file/t07f9605a9, just click on any of the button with a green arrow. It's only 40 MB, music is compressed as OGG format so you'd need something that can play that kind of file if you want music. You probably need Winrar to unpack the file. Alternatively you can find your own favorite pirate site which should have it too.
Everything besides dialogue has Engrish subtitle so it should not be too hard to figure out what's going on.
You're Cirno, the fairy of ice. Hold shift to move slower. Hold Z to charge up Ice Wall and release Z to use it when you hear the 'click' sound. X for Perfect Freeze (bomb, snowflake icon on bottom left). Hold C for turbo fire, or you can hit Z repeatedly and hurt yourself from the repetitive motion. I think you're always in the slow mode while charging up for Ice Wall. Ice Wall freezes all bullets except lasers and flaming shots. Your freeze power appears above your character while charging an Ice Wall and it's the 2nd number on the right side. You need at least 30% freeze power to charge up Ice Wall, and Ice Wall uses up all your freezing power. Higher % leads to longer duration freezes. Your life bar is on the right top and it starts at 200%. Losing a life decreases it by 100% and if it goes negative it's game over.
Your shot power, points, perfect freeze meter, and life bar are all increased by freezing stuff. Defeated enemy drop blue icons that give you points. Freeze meter is increased over time, but charges up faster if you're close to bullets (without dying), moving in slow mode, or shooting stuff.
There are 3 bosses that you face: Sunny, Luna, and Star. It should be obvious who is who based on the background even if you can't read it. The route determines which order you fight them. The first stage boss never has any Ice Wall piercing attacks. The second stage boss will have flaming shots, and the third stage boss will always have flaming shot and laser. In the final stage you only have to defeat the leader but her two sidekicks have far less health and does a lot of damage themselves.
This is the first Touhou game in the last 4 or so where continuing after you died actually sends you to where you died instead of beginning of the stage, though I needed all my continues to just get past stage 3. Lasers will shoot straight through Ice Wall and refract in multiple directions at the same time, so basically never use Ice Wall near lasers (easier said than done). If you beat all the 6 routes you can unlock the extra stage and fight Marisa Kirisame, though you'd have to at least be able to beat Normal without continuing to have a reasonable shot at the extra boss as per tradition. Route A/B/C determines where you start, and at the end of stage 1 you'll be asked where to go, and this will determine which path you end up. Sunny seems to be the hardest if you leave her to the end (A1, B1?).
There's probably an English patch somewhere. The dialogue is actually quite hilarious.