A solid rogue-like deck building game that has grid-based combat with an emphasis on simple, generic core characters or classes but vast card and equipment variety.
Deck building: The deck building would not need to be especially complex or innovative. Just have many simple cards that allow characters to move, deal damage, gain block/shield, draw cards, etc., along with more complex cards later on.
Combat: Turn-based, grid-based, like many TTRPGs like D&D5e and PF2e. Nothing too fancy or complex, just a grid with obstacles and entities occupying it. Maybe skip verticality to simplify things. Maybe all characters gain some movement at the start of each turn, so that movement isn't entirely reliant on the cards they have.
Characters/Classes: Instead of highly specific characters with specialized starting decks and card and equipment availability, have them possess only a few unique cards in their decks, and maybe have a unique ability or different stats. E.g. a Warrior class could start with more HP and a solid melee weapon, along with 2 cards that allows them to gain block/shield and deal damage. Something simple. A ranger class could start with a ranged weapon and be able to move more at the start of each turn, or something of the sort. The idea is that the characters have clear strengths and weaknesses at the start, but are flexible enough that you can build them however you'd like. A bit similar to the characters in The Binding of Isaac maybe. There, the characters (ignoring the tainted versions) have different stats and starting items, which make them lean into specific playstyles, but they can be taken in any direction.
Equipment/Gear: Characters can be equipped with armour and weapons, which add cards to the character's deck or alters the character's stats. E.g. maybe an Armour Rating stat could provide a flat damage reduction when taking damage, or maybe it instead provides additional block/shield when using a card that grants block/shield. One interesting design decision would be how weapons would work. They could just alter a Damage stat, which damaging cards then utilize (E.g. a basic Strike card that just deals damage to an enemy in melee, which scales off the Damage stat), or they could provide cards themselves. E.g. if you have a Longsword equipped, the effect of the Longsword is to add 3 Longsword Attack cards into your deck, which maybe costs 1 Energy/AP to use and deals 5 damage. If you instead equip a Dagger, it could add 5 Dagger Attack cards instead, which maybe cost 0 Energy/AP to use and deal 2 damage. Unique weapon drops could add strong, unique cards to your deck, or maybe just proc unique effects when used to attack foes.
Gameplay Loop: Not too picky here. The game could just function like Slay the Spire and it'd be fine. You jump into a run, select a character, select which paths you take, fight some foes, gain some cards and equipment, and eventually either win or lose the run and start over. Meta progression would keep the game fresh.
Something like that. There are games that are trying similar things (like Tendryll, though it seems abandoned), but I have not seen a finished game that fits the description that well.
