AI had gotten so much better at reasoning and simply handling our questions. But, what's much harder is solving a problem where every answer depends on dozens of other answers — and a single mistake can throw off the entire solution.That's why a new demonstration of OpenAI's GPT-5.6 Sol Pro caught my attention this week. AI researcher Riley Goodside shared what looks like one of the most unusual reasoning tests I've seen: an empty crossword puzzle created by Claude Fable 5 Max, containing the first 150 Pokémon. But the catch is that ChatGPT wasn't given a single numbered clue.Instead, it had to fill in the entire crossword by reasoning from the intersecting letters and the overall structure of the puzzle alone.Why this is more impressive than it soundsChatGPT 5.6 Sol Pro solves an empty crossword puzzle (made by Claude Fable 5 Max) with the first 150 Pokemon without any individual numbered clues: pic.twitter.com/oCjgVfYoNEJuly 13, 2026At first glance, it looks like a fun Pokémon challenge. But when we look closer, it's much closer to highlighting the kinds of problems AI actually faces in the real world.While traditional crosswords are solved one clue at a time this puzzle works differently. Without individual clues, GPT-5.6 Sol Pro had to determine where every Pokémon belonged while ensuring every crossing remained consistent. One incorrect placement could force dozens of downstream corrections. This was a massive constraint-satisfaction problem.Those are exactly the kinds of challenges AI agents encounter when they're debugging software, planning workflows, coordinating multiple tools or editing large codebases.Why Pokémon actually makes this harder