That title screen is one of the most beautiful in the jam. Detailed pixel art of a red haired ninja with a high ponytail, black mask and huge Wolverine style claws, the title in letters that each have their own colour, and her silhouette repeating as a background pattern. It looks like a Mega Drive box. The character sprite is excellent.
And the name is the thesis. DOPEAMINOYD with the combo as a survival mechanic is a joke about addictive game design itself: you don't hold the combo to score, you hold it to NOT DIE. The dopamine loop became a life requirement. That's a smart bit of framing and the rainbow combo counter under the white SCORE, each digit a different colour, is tacky in exactly the right way. It says "this is the number that gives you pleasure" without a word.
The HUD is clean too, health in red, SCORE, the coloured combo, level in cyan, the ability icon on the side and a discreet "Z - help" in the corner. The dark grey pixel art cave with hanging green vines is well made and the character stands out against it. Controller support with the triggers documented on the page is a nice extra.
Three notes. I walked a fair distance and didn't find a single enemy in the first stretch, so my score stayed at 0. In a game built entirely around holding a combo, opening with nothing to attack empties out the first impression, which is the one most jam voters will get. It also wasn't clear which key attacks, I tried X and saw no animation, and only noticed the "Z - help" afterwards. And the cave is dark and monotonous, the grey platforms against the grey background blur together a bit.
The art and the concept are above average here. It mainly needs to drop the player into the action faster.