From the UFO 50 website:

AUTHENTIC BUT ALSO MODERN - We carefully chose what elements to modernize. Every game shares a unique 32-color palette and we took great efforts to make them look and sound like actual 8-bit titles from the 80s. On the other hand, it was important to us that UFO 50 was fun and surprising for modern players, so we chose not to limit ourselves to the genres and design conventions of the past.

They’ve said in interviews as well that they choose to view UFO soft as a game company that was very ahead of its time