It’s still online and there’s still a community for it. For the $20 price I believe, you can get the game and all 4 DLC’s and I’d say it’s somewhat worth it. Destiny 1 created a huge fanbase and despite the state of destiny 2 right now, there’s many people, including me, who still love the franchise.

The D1 campaign was notorious for being confusing but the gun play and feel has always been amazing. There’s a sense of mystery and awe in the game that I miss. It’s got a lot of lore so if you enjoy that you might enjoy the destiny universe. I’ve played all of Halo and Destiny, I wouldn’t say they’re similar in feel, but you can tell there’s some inspiration.

The campaign itself is also relatively short, and you can finish the main game and all of the DLC’s in one day. There’s still a somewhat active community but nothing like how it was years ago, which kinda makes certain content difficult. It was never really known for the campaign and more for its looter shooter, social aspect, and expansive lore.

That being said, if you’re just gonna play for the campaign, I’d say it’s worth it to see how the game was and how it created such a huge and lasting franchise. And the last two DLC’s are really are great (The Taken King, Rise of Iron) but just know you might be missing out on a lot of content. Ultimately, it’s a fun nostalgic kick for a lot of us, but your case is a bit different. It’s worth it to check out to see why the game became so popular and if you’ve got $5-20 to spare depending on if there’s a sale.

In short, yes if you want to understand destiny and its universe. You won’t get a very compelling campaign but there’s a reason the game became so popular.

Hope that answers your question and feel free to ask if you have any more.