Cosmos Era

Cosmos Era is a free hard sci-fi idle game that runs in your browser. Start at the Big Bang and play through 12 eras: particles, the first stars, chemistry, early life, humans and finally an interstellar civilization.

Every unlockable node cites a real source (year, people, paper), and invented parts are labeled as game lore. One light-year in the game equals one real hour, and nothing travels faster than light. 16 endings, 118 research cards, a crafting table based on real nucleosynthesis, and 12 alien civilizations inspired by Fermi paradox solutions.

Free to play with no ads and an optional supporter membership. Available in 10 languages.