Fushigi na Mori no Pokora [1 loop, Normal] (PC)

An old doujin game popular enough to be featured on the Japanese wikipedia, as it was the winner of the Japanese Free Game Awards back in 2004 [These guys also made Fortune Summoners on Steam]. A chasing game where you try to grab all the pokora (raccoons?) before the time limit! Use the acorns for better equipment, and master the drifting dashes!

Menu: Z/A = back, X/S = confirm
In-game: Z/A = jump, X/S = dash, arrow keys to move around.
ESCAPE EXITS GAME, BE WARNED

When you're down, mash jump and dash to recover.
Green warnings will warn you of harmless obstacles. (you won't go down)
Blue warnings will warn you of dangerous obstacles you can jump over.
Yellow warnings will warn you of dangerous obstacles you can't jump over.

Setting up the game is probably most of the work. It starts in full screen which seems pretty ugly. Here's how to go windowed:
オプション (2nd option) -> スクリーンモード (3rd option) -> ウィンドウモード (2nd option). Then heading back to the main menu will apply the changes. (In the options, おんがくのボリューム and こうかおんのボリューム will change music/sfx level). When starting the game, you will have to create a profile first (さいしょからはじめる). Enter some name, then press おわり to confirm. Press confirm at the next screen (it's about classes but we'll just take the normal one). The left should now show a list of ステージ (stages). Here's where you ready up.

Starting point: Pressing X when cursor hovers over ステージ１ (after putting in your name and selecting "class")
Ending point: Finishing ステージ6 (5 pink, 4 blue, 3 white)

You can use the acorns you collect from the raccoons to buy better equipment. If you press right in the stage select, the first option is for buying new equipment. Give it a look before playing the game.
Losing a stage will first show you all records so it takes some time. The game over screen itself has 3 options, retry stage, go to the shop, or go back to stage list (avoid this or you'll have to do the previous stage again).

It's possible to finish these set of levels under 10 minutes if done well. (unfortunately this non-full game relies on loops, so there's only these 6 levels)