You mean the original they shut down to make you play Overwatch 2, or Overwatch 2 which is still playable now even though they cancelled PvE which was supposedly the reason the game is a sequel, but was really a pretense to switch the game to a F2P model, then the PvE was likely cancelled because Activision realized that matter how amazing the PvE was, for the time it was taking to develop it wouldn't bolster their F2P sales significantly in the long term so it wasn't worth making.
That said, Overwatch 2 is still playable.
This isn't in defense of Overwatch 2, I'm just saying it's still there if you want to play it.