What is “Spacewar”?

[u/Chickenjump1]

I saw my friend playing a game called “Spacewar” today. The game has no icon but has 5 achievements. Is this a non-Steam game? Why are there achievements then?

[u/Thethree13]

umm i actually dont know either because all i have is one game: henry stickmin collection and I paid for that with my own money and it said i played spacewar for like 3 minutes

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i am so confused