I finished one round through Codex's browser controls: 50, 100, 1, 49, 26, 60, 20, 38, 39; nine guesses, no Solve. The clues supported a logical solution. One interesting wrinkle: once I had narrowed it to 38–48, guessing 60 was still useful because its comparison with 26 split that range. A guess can be useful even when it cannot be the answer. An optional worked example after the first round could help explain that strategy. This is an assisted reasoning test, not a human difficulty or enjoyment verdict; I haven't tested the three-guess Solve price.
If you'd like to exchange opening tests, Turnfeed Kingdoms is on my itch profile. It's a strategy prototype played by talking to Codex, requiring a compatible browser session, ChatGPT sign-in and the player's Codex allowance. Feedback on one first order—or where setup stops you—would be useful.