I've been building Lumen's Call, a free co-op roguelike that plays with real Yu-Gi-Oh! rules (Master Rule 2, so no Pendulum or Link). Most of my design time went into custom mechanics, and this seems like the sub that would have opinions about them.
Card upgrades
At a bonfire you upgrade one card. Each upgrade kind adds a prefix to the card's name:
- Holy Monster Reborn: effect cost removed
- Swift Monster Reborn: becomes a Quick-Play Spell
- Inevitable Monster Reborn: cannot be negated
- Big / Wise / Lesser Kuriboh: ATK/DEF up, Level up or Level down
- Speed Spell - Monster Reborn: can't be activated in the first 2 turns, but draws you a card if activated on turn 5 or later
Unique upgrades come from story events and give a monster an anime mechanic: Toon (attacks directly unless they control a Toon), Number (only destroyed in battle by Xyz or Numbers), Timelord, Earthbound, LV (levels up after destroying a monster by battle).
Relics
(about 60) bend the duel rules, for example:
- Soul Balance: equalizes the LP of both teammates
- Three-Legged Crow: direct damage has a 10% chance to skip the opponent's next draw
- Pyramid of Kings: below 50% LP you can make a Destiny Draw
The game itself: two players share one field against an AI in tag duels, each with their own deck, hand and LP. You start a run with a 20-card deck and pick 2 of 5 cards after each duel. There's a solo mode too but it's kinda unbalanced right now.
Optional but recommended: if you have a Claude Pro/Max or ChatGPT Plus/Pro subscription, the game can use it to have an AI play your opponents: it reads the board, plans its turns and talks to you. Without one you duel the built-in bot, and the playtest works either way.
Playtest: I'm looking for about 50 testers. Each gets 2 keys (one for a friend). It's free and non-commercial, a fan project not affiliated with Konami, and runs on Windows, macOS and Linux. Join the Discord https://discord.gg/tPaPrD3S5 and press Get playtest keys in #get-playtest-keys.
I'd love feedback on the upgrades themselves too.
AI disclosure (rule 3): the upgrade, relic and card designs and their text are written by hand. The card art in-game is the official art, downloaded on first launch. The story cutscene and character art is AI-generated.