SeaKing

One Piece Card Game sim with an AI opponent

Most OPTCG sims put you in a deck builder with nobody sitting across from you. SeaKing gives you the opponent.

Play vs AI Review the game afterwards

How the SeaKing AI picks its move

Every turn the bot builds the list of moves the rules allow it, then searches that list with alpha-beta pruning. It plays your likely replies out several plies deep, scores the boards that come back, and keeps the line that scores best. Nothing about that is a script. Hand it a deck it has never piloted and it works out the plan from the position in front of it.

The search runs in a background worker thread with a time budget per move, so the page keeps taking your clicks while the bot thinks. That budget is why it answers in a second or two instead of freezing the tab.

What comes out of it is the ordinary competitive stuff you want a practice partner to do. It blocks when the block saves more than the blocker costs. It holds counter cards for the attack that matters instead of spending them on the first swing. It counts your life and goes for the kill on the turn the kill is there.

The AI does not look at your hand

This one matters more than the search depth. The bot's own planner blanks your hand before it runs, so it works from the same hidden information a person across the table would have: your board, your trash, your DON!! count, your life. Beat it and you beat something that was guessing about your cards, same as you were guessing about its cards.

What the AI can see

  • Your leader and characters
  • Your life total
  • Your DON!! count, rested and active
  • Your trash

What the AI never sees

  • The cards in your hand
  • The order of your deck
  • Which counter you are holding
  • Your face-down life cards
The search runs on a copy of the board with your hidden zones blanked out, so its plan comes from reads rather than knowledge.

Four difficulty tiers, from Easy to Hard+

Easy
Plays reasonable-looking moves without searching. Good for a first game while you learn where the buttons are.
Medium
Takes the best immediate trade it can see. It will walk into a two-turn plan you set up.
Hard
The default, and the first tier that searches. This is the one to measure yourself against.
Hard+
The same search with a deeper budget. It thinks a little longer per move and slips less often in messy board states.

Learn mode sits alongside the tiers. It keeps the rules prompts on screen and lets you take a move back, which is the setting to use while the phase order is still new.

Decks the SeaKing AI can pilot

The preset lists come from tournament results, so the bot's draws and lines match what you would face at a locals. You can also point it at a deck you built yourself in the builder and it will pilot that instead. Testing your own brew against an opponent that plays the matchup properly is the whole reason the search is deck-agnostic.

Check your read with the hint button

The hint button runs the same search on your side of the board and tells you the move it rates highest. Use it as a second opinion on the turns you are unsure about. Pick your line first, then ask, then compare. That is closer to how you improve than being told the answer before you have thought about it.

One Piece Card Game AI opponent FAQ

Does the AI see my hand?
No. It sees your board, your trash, your DON!! and your life, the way a real opponent does.
How does it decide what to play?
Alpha-beta search over its legal moves each turn, run in a background thread with a time budget.
What difficulty should I start on?
Learn mode if the game is new to you. Hard once you know the phases.
What decks does it play?
Tournament lists, or any deck you build yourself.
Can I see how it decided?
The hint button shows you the move its own search rates highest.
Is it free?
Yes. Browser only, no account, no download.
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