A pretty interesting gameplay twist for a puzzle platformer.
The art is quite well done and the music and sound effects are good.
Animation is decent enough.
The physics and control is reasonable enough although it could do with some fine tuning, collisions can make navigating enclosed areas awkward and the game could do with some coyote time to jump when you walk off a platform.
The use of the arrow keys make it awkward to position my fingers properly to jump, duck and move left/right at the same time so changing the jump key could help with that.
It was a bit awkward up front using the main menu as it took some guessing to figure out you had to press Enter to use the selected option. The selected option colour also doesn't stand apart enough from the unselected options.
The mechanics are quite simple once you grasp them but it's difficult to see how it ties into the jam theme as needing to fall into spike pits to gain some cards feels tacked on to meet the theme.
It's also a bit odd why the game is in a portrait aspect instead of landscape in line with widescreen displays.
Puff is pretty decent as is and could definitely be expanded with some more ideas/mechanics, content and polish.