Resolution will be based on Nintendo's official Investor Relations information.
If at any point before 2025 in any of Nintendo's updates to the Top Selling Title Sales Units financial data (https://www.nintendo.co.jp/ir/en/finance/software/index.html), 'The Legend of Zelda: Tears of the Kingdom' is listed as having more copies sold than 'Super Mario Odyssey', this market will resolve to YES.
If 2025 begins and Nintendo has never released data showing that TotK has sold more copies than Odyssey, this market will resolve to NO.
For reference, at the time of market creation, 'Super Mario Odyssey' is listed as having sold 25.76 million copies as of the March 31st, 2023 update to the figures.
18.5 million sold between May 12 and the end of July...I would be pretty surprised if it didn't end up passing 26 million by mid-2024.