I've been keeping a timelog, so I figure I might as well post it here:
1:04
Basic platforming controls, health system implemented
4:19
Added blood floor painting, health, health pickups, enemy
7:05
Different weapons implemented, weapon state machine implemented, aiming system, weapon swaps
9:23
Weapon slot UI implemented, weapon pickups implemented
10:06
Started implementing the beginning of the shop, including menu screens, fixing meat pickups
12:00
Added stat shop with scaling prices, gold, reworked UI
12:39
Added another weapon and changed the weapon framework
13:49
Implemented enemies and player damage
14:30
Implemented different weapon mechanics: shotgun and machine gun
15:40
Implemented the blood exploder
18:00
Improved the stat shop, added icons, borders. Added fonts and themes.
20:09
Coded the opening cut scene, including animations, run counter and text boxes
20:43
Added death tracker, crates, changed shop menu
21:33
Added special icons for each weapon, made crate destruction permanent