Normal sudoku rules apply. Once in each row, column, and box, the Thing assimilates a number, thereby negating it (e.g. if the Thing is in R5C7 and the cell appears to contain a 3, its actual value is –3). Values on the blue line have the same sum in each 3x3 box the line is in. Values along a thermo increase from the bulb end. Adjacent values on a green line differ by 5 or more. Numbers in a circle appear once in the four surrounding cells; they may be genuine (positive) or they may be the Thing (negative). To successfully escape, you must travel from the now destroyed Outpost #31 (R2C2) to the helicopter (R8C8). Your path is one cell wide and may not go outside of Antarctica's boundary (blue line). The path which travels orthogonally may not contain nor be orthogonally adjacent to any of the Thing's cells. Adjacent values on the escape route differ by 5 or more.