Sesame Street Elmo's 123s is based on the 1980s computer game Astro Grover, where Astro Grover character is swapped out for Elmo , who was popular for Sesame Street in the 1990s and 2000s. Elmo needs to help aliens with numbers in order to build their house.
The gameplay revolves around matching numbers to unlock doors and progress through levels. The game features a variety of educational elements, such as counting and basic math skills, which were popular on Sesame Street during the 1990s and 2000s.