Chess Assistant 26 / Aquarium 2026 (ChessOK) review: scores and evidence

A1 :1Importing your games (Chess.com, Lichess, PGN files)

https://chessok.com/?page_id=27947: file-based management of databases and games; no Chess.com/Lichess connection mentioned.

A2 :3Automatic engine analysis of every game

https://chessok.com/?page_id=27948: Stockfish 17.1, IDeA, CAP; depth set by the user, no quota (local software).

A3 :0Recurring mistakes identified across all your games

https://chessok.com/?page_id=27947: no mistake named across several games

A4 :0Types of mistakes covered (tactics, strategy, endgame, time…)

https://chessok.com/?page_id=27947: no typology of mistakes

A5 :0Written explanation of each mistake

https://chessok.com/?page_id=27948: numerical evaluations and trees; no explanatory text

A6 :0Stated verification of the diagnoses (procedure, rates)

https://chessok.com/?page_id=27948: no mention of reliability.

A7 :0Tracking each weakness over time

https://chessok.com/?page_id=27947: no progress history mentioned.

A8 :0Comparison with players of the same rating

https://chessok.com/?page_id=27947: no comparison to a rating band.

B1 :2Building a personal repertoire

https://chessok.com/?page_id=27948: "chess trees" and editable opening trees; no suggestion from the player’s games.

B2 :1Training the repertoire (drills, games)

https://chessok.com/?page_id=27948: reading through the trees; no interactive drill mentioned.

B3 :0Spotting where you left your repertoire in your games

https://chessok.com/?page_id=27947: no deviation detection mentioned.

B4 :2Verification of the lines taught (engine, practice)

https://chessok.com/?page_id=27947: "Chess Opening Encyclopedia" backed by ≈ 9.5M games (sourced); no protocol published.

B5 :2Opening explorer and statistics

https://chessok.com/?page_id=27947: database of ≈ 9.5M games, weekly updates; no online database or player merge.

B6 :1Explanation of opening plans and ideas

https://chessok.com/?page_id=27947: encyclopaedia = names, moves and statistics; explained plans not found.

C1 :0Exercises drawn from your own games

https://chessok.com/?page_id=27947: no exercise from one’s own games mentioned.

C2 :2Bank of tactical exercises (size, themes, rating)

https://chessok.com/?page_id=27947: Premium includes 1 year of Chess King Learn, "135+ courses"; https://chessok.com/?page_id=27966 "More than 200,000 exercises" (Chess King Complete); adaptive rating and quality control not found.

C3 :1Endgame training

https://chessok.com/?page_id=27947: endgame courses through Chess King Learn; no dedicated module in Chess Assistant.

C4 :1Strategic and positional training

https://chessok.com/?page_id=27966: Chess King Learn courses (passive content included); no positional exercise of its own

C5 :0Training defense and alertness

https://chessok.com/?page_id=27947: no defensive exercise

C6 :0Training calculation and visualization

https://chessok.com/?page_id=27947: no mention of calculation/visualisation exercises in the software.

C7 :1Difficulty matched to your real level

https://chessok.com/?page_id=27966: Chess King courses by level "ratings 200–2400"; no adaptive rating mentioned.

C8 :0Spaced repetition (named algorithm)

https://chessok.com/?page_id=27947: no spaced repetition

C9 :0Personalized training plan

https://chessok.com/?page_id=27947: no training plan

D1 :0What the free plan actually lets you do

https://chessok.com/?page_id=27966: paid software; no free version (only 1 month of Chess King Learn included with Chess King 26).

D2 :0Annual price of the full plan

https://chessok.com/?page_id=27947: CA 26 Premium $199.50 ≈ €183 (licence); > €150.

D3 :1Commercial transparency (price shown, trial, cancellation)

https://chessok.com/?page_id=27966: prices displayed; no trial or refund policy found.

D4 :1Number of paid tiers (how simple the offer is)

https://chessok.com/?page_id=27966: three paid products (CA 26 $109, CA 26 Premium $199.50, Aquarium 2026 $69.95); Premium does not include Aquarium

E1 :0Published evidence of effectiveness

https://chessok.com/?page_id=27966: no effectiveness data.

E2 :0Chess verification of the content (positions, lines)

https://chessok.com/?page_id=27947: no information on content verification.

E3 :2Transparency of the method (algorithms, code)

https://chessok.com/?page_id=27948: engines named (Stockfish 17.1, Rybka 4), IDeA/CAP described; no code or full documentation.

E4 :2Marketing claims that can be checked (no overselling)

https://chessok.com/?page_id=27947: factual wording (databases, engines, discounts); limits not stated.

F1 :2Courses organized by rating level

https://chessok.com/?page_id=27966: Chess King Learn courses "levels 1–9 (ratings 200–2400)"; the path by band is not presented as a continuous curriculum.

F2 :2Course authors named and titled

https://chessok.com/?page_id=27966: courses by Dvoretsky (IM); a team of ≥ 3 titled authors not found on the page.

F3 :2Content formats (text, video, interactive)

https://chessok.com/?page_id=27947: text + interactive exercises (Chess King Learn); no video mentioned.

F4 :1Published method of progression

https://chessok.com/?page_id=27966: recommended levels per course; no curriculum with milestones published.

F5 :2How often the content is updated

https://chessok.com/?page_id=27947: 2026 versions and weekly database updates; no dated changelog for the software.

G1 :1Playing humans online (pool, anti-cheating)

https://chessok.com/?page_id=27947: "Chess King Playing Zone" (play.chessking.com); no online-player counter published.

G2 :1Realistic artificial opponents

https://chessok.com/?page_id=27948: "grandmaster-level playing program" and engines; levels, no personalities or human model.

G3 :2Replaying one specific position against the machine

https://chessok.com/?page_id=27948: play/analyse any position from one’s databases against the engine (local software); nothing automatic.

G4 :1Tournaments and organized competition

https://chessok.com/?page_id=27947: tournaments on Chess King Playing Zone, frequency not published.

H1 :0Platforms available (web, iOS, Android, desktop)

https://chessok.com/?page_id=27948: "PC (Download)"; Chess Assistant/Aquarium are Windows only.

H2 :0User ratings and reviews (stores, press)

https://chessok.com/?page_id=27966: no store listing or rating; no recent third-party review consulted.

H3 :0Interface languages available

one language found — https://chessok.com/?page_id=27947: no interface language indicated; page in English.

H4 :0Accessibility (keyboard, screen reader)

https://chessok.com/?page_id=27947: no accessibility mention.

H5 :3Offline use and known incidents

https://chessok.com/?page_id=27948: local software, everything works offline (download).

I1 :1Preparing for a named opponent

https://chessok.com/?page_id=27947: databases of 9.5M games (browsing a player’s games); no preparation report described

I2 :1Annotating and sharing games (studies)

https://chessok.com/?page_id=27948: IDeA and "chess trees" (saved analysis); no sharing by link described

I3 :1Entering a game played at a club (photo, scoresheet)

https://chessok.com/?page_id=27947: "managing chess games and databases" (game entry); no photo or OCR

I4 :1Searching your games (filters, position)

https://chessok.com/?page_id=27947: database management; filters/position search not described on the page

J1 :0Access to human coaches

https://chessok.com/?page_id=27966: no access to coaches.

J2 :0Size and activity of the community

https://chessok.com/?page_id=27966: no forum or visible community.

J3 :0Tools for trainers, clubs and schools

https://chessok.com/?page_id=27947: no coach/club area mentioned.

J4 :3Engagement mechanics (streaks, virtual currency, reminders)

https://chessok.com/?page_id=27948: local software with no streak, leaderboard or nagging.

K1 :2Exporting your data (games, repertoire)

https://chessok.com/?page_id=27947: databases exportable as game files (database software); personal-data export not applicable.

K2 :0Protection of personal data (GDPR, hosting)

https://chessok.com/?page_id=2: no privacy policy found on the site.

K3 :1Public API and source code

https://chessok.com/?page_id=27947: standard database formats; no API or open code.