 Upon completion of each puzzle , the player 's performance is compared on a leaderboard based on the number of instructions placed in their reactors , the number of cycles it took to meet the quota , and the number of reactors required to meet the solution . The player also has an option to upload videos of their solution to YouTube . The player , once having cleared a puzzle , can return to previous puzzles to try to improve their solution by reducing the number of instructions , cycles taken , or reactors used . SpaceChem supports downloadable content created by the developers themselves , and user @-@ submitted puzzles through its ResearchNet service . A later addition included an open @-@ ended sandbox mode where players could simply explore the game 's capabilities . 
