The problem Onchain Mecha solves

Each warrior Mecha has a unique trait combination.
The traits are randomised in the contract to generate thousands of weaker jumbled variant versions.
Players must mint packs of cards (or swap with other players) and build a collection of the 7 mechas with the correct trait combinations. Cards with the correct combination are identifiable by a kanji/symbol in the top left corner and a border. There are sets of the True-Cards to be found, these are the 7 basic Mechas - collecting all 7 will unlock a True-Card version of Aku. Among the cards there is also another much smaller set of Rare-Cards; the mechas, but super powered, with some quirky variations. Players can try to collect a full set of these as well. There are also various individually unique Super-Rare cards that have some additional fun trait features from the cryptoverse to be found.
Lurking in the contract are only 7 Ultra-Rare Aku Cards. Should one collector manage to collect and hold 3 or more of these cards in one collection it gives them the power to trigger a 'Doomsday' contract which will destroy the Entire Mecha Universe.
In the hopes of maintaining the universe players must collect all 7 mechas and if lucky enough to mint an Aku Ultra-Rare to hold it captive and prevent one person from amassing three or more.

The cards are composed of 7 distinct traits on different layers :
1. background
2. appendages
3. pod-interior
4. mecha body
5. rider
6. environmental overlay
7. a Japanese kanji/symbol and border.

Challenges we ran into

On the art/concept side :
Coming up with a sort of unique concept around a flexible manga-inspired svg project (not just another pfp project) was a bit of a challenge. Being original is tough. Once we settled on the idea of creating a trading card system, our focus shifted to conceptualizing compatible traits and layers. Gamifying the concept presented another hurdle to overcome and ensuring that the intricate SVG artwork remained suitably streamlined for deployment within the contract was a concern of mine. However, Elliot's coding expertise provided us with considerable flexibility in that regard, which I greatly appreciated.

Crafting a narrative for the website presented another creative hurdle, especially given the need to meet a tight deadline and to try work as much as possible with the assets we already had at hand - though a lot was created for it including the fonts. To keep the project momentum going, we made numerous swift decisions, recognizing that not all of them may have been perfect, but they kept us from getting bogged down in endless deliberation. Overall, this approach largely paid off.

I would always love to go back and refine the art, change line weights and colour choices and even refine the entire concept, but at some point you have to let something go and put those considerations down to learning.

On the technical side:
We had several trial and error sessions while trying to get the SVG files to generate as contracts. The sheer amount of off-chain logic to build the contracts programatically plus the amount of onchain logic used to render them was a big hurtle.

The card minting randomization is made possible by the use of RANDAO. When you mint a pack it selects a block that is in the future and only upon that block being passed can you mint the cards in the pack.

Note: The we have been working on the generated SVG contracts for nearly a year. The actual deployment and website are what we have accomplished during this hackathon.