Classic Games

CKSTEM Go Arena

Grades 2+ · academy, bot, pass-and-play & live arena

Learn Go — the oldest, deepest board game, and the simplest to start. A discovery-first Academy of 24 skills across 5 paths (capture, the ladder, good shape, two eyes, life & death, territory) with 1,300+ engine-verified guided puzzles — fewer but sharper: each a genuinely different read, now including a Classic Tsumego category of real multi-step problems from the great masters (Gokyo Shumyo 1812, Xuanxuan Qijing, Guan Zi Pu, Go Game Guru), every one re-proven move-by-move by our own solver, plus the net (geta) and the capturing race (semeai) — and an adaptive trainer that tunes difficulty to each learner, a Daily Challenge, a built-in AI game review (the Coach) that runs entirely in your browser, a coached teaching mode that takes back blunders so you can retry, a bot ladder from Grabby to The Sage (a real tree-search engine), Capture Go and Full Go on boards up to 19×19, pass-and-play on one device, SGF save, and live class arenas. Teaching first — free, no login.

For Educators

Built for the classroom

Strategic thinking in a game where the mathematics is visible: liberties and capture (a group is a connected component; capture is when its open-neighbour count hits zero), the ladder as a forced sequence you read to the end, counting in capture races (parity), the small theorem that two real eyes mean unconditional life, territory and komi (area and fairness / expected value), and why Go is the game that beat brute force (Monte-Carlo Tree Search and AlphaGo). It is discovery-first: every idea is something the student SEES happen on the board and then names — never a rule told up front. After each solve a “Why this works” note explains the idea, so even a lucky guess teaches something.

Grades 2 to all ages. Boards from gentle 5×5 up to 19×19 (Pass & Play and review go to full 19×19; the bot plays up to 13×13), Capture Go (first to capture wins) as the on-ramp and Full Go for depth. Nothing is locked — the Academy suggests an order but every lesson is open from the start; only the boss-earned “Theorem” is gated.

Three ways to play

CKSTEM Go Academy (guided practice)

22 populated skills across 6 learning paths (First Captures → Reading Lab → Life & Death School → Captures & Ko → Whole-Board Start → Classic Tsumego), each with bronze→diamond tiers — 1,300+ DISTINCT puzzles (we deliberately cut hundreds of near-duplicate positions — generated AND cross-collection — in favour of fewer, sharper, genuinely-different reads). The headline is a new Classic Tsumego category: real MULTI-STEP problems imported from the masters (Gokyo Shumyo 1812, Xuanxuan Qijing c.1349, Guan Zi Pu c.1660, Go Game Guru) — you read a whole forced sequence to capture, kill, or make life, and every one is re-proven move-by-move by our own solver. Plus the net/geta, the capturing race/semeai, and Shape. Every tactical puzzle is re-checked by an exact solver (life-and-death uses the classic vetted shapes), so the technique is real. An adaptive trainer serves problems in a smooth difficulty ramp and tunes to each learner — harder after a quick solve, gentler after a struggle, never locking anything. Hints help you SPOT the idea without giving it away, a “Why this works” note follows each solve, a Daily Challenge gives your whole class the same set each day, and a 🔍 Diagnose mode interleaves mixed problems with the technique hidden until after you solve — training you to READ the position instead of pattern-matching a labelled drill.
Play vs the bot

Climb a six-step ladder from Grabby to The Sage — a real tree-search engine (alpha-beta reading in Capture Go, a UCT tree in Full Go) that runs entirely on your device. Each rung removes one idea, so a true beginner can actually beat the early bots. Turn on “Coach undo” and a move that would lose you a group is taken back so you can try again. Choose Capture Go or Full Go, komi and handicap, on 5×5 to 13×13.
The Oracle — optional neural opponent (19×19)

On the full 19×19 board, The Sage becomes a small open Go neural network (a KataGo-derived policy net) that runs 100% in your browser — a one-time ~6 MB download, then cached; no server, no account, no per-move cost. It plays real whole-board Go where our classic engine is weakest, and our exact solver still backstops its tactics. It’s honestly labelled experimental (a small net, not AlphaGo) and is OPTIONAL: it needs a reasonably modern device with WebGL/WebGPU; on devices that can’t run it (or it’s too slow), the game quietly falls back to the fast classic bot — nothing is lost.
Coach game review (built-in AI review)

After any game vs the bot, the Coach replays it right in your browser — no server, no account — and shows a win-rate graph, marks each blunder and inaccuracy, names the 2–3 turning points, and shows the move the engine preferred as a ghost stone. Exact solver findings (a group left in a ladder, a capture missed) are labelled PROVEN; the search numbers are honest estimates. Save any game as an SGF file to replay or share.
Pass & Play (solo/home)

Two players share one device, placing stones and capturing. No login, great at home or on one shared laptop.
Host a live arena

Open a room on the projector; a 4-letter code + QR + join link appear. Pick a board (7×7/9×9/13×13), then watch live mini-boards fill as a ladder climbs. Students play best-of-2 Capture-Go duels (each goes first once — that swaps the Black advantage, so it’s fair); the odd student out plays the beatable Grabby bot so nobody waits.
Join on any device

Students enter the 4-letter code (or scan the QR / open the link) on a laptop, tablet, or phone and get matched against a classmate. When a match ends they’re instantly re-paired — no waiting, no elimination.

Run a live class in 5 steps

Open CKSTEM Go Arena and choose Host an Arena — pick the board (Small 7×7, Classic 9×9, or Big 13×13) and the session length.
Share the 4-letter code / QR / link; students join on any device.
Hit “Open the Arena”: students play best-of-2 Capture-Go duels — they swap who goes first (plays Black), so it’s fair. First to capture wins the round.
Watch the live ladder climb and the mini-boards fill on the big screen; an odd student out plays the beatable Grabby bot so nobody sits out.
When time’s up the podium crowns the ladder. No accounts — the ladder lives only while the room is open.

Tip: host on a laptop or projector (the big screen shows the code, QR and leaderboard); students join on their phones or laptops.