Are the servers even still live?

Haven't played for awhile but had an itch to play recently. Game starts up fine but when I click on "Play Online" the game just instantly crashes to desktop. Checked the steam charts and noticed this game is pretty much dead and the last forum post is nearly a month old. Mainly just wanted to know if it was something on my end or if the game is just straight up dead and the servers are down.

The game is working fine for me.  Just tested and Play Online works with no issues.  You might try the "Verify Integrity of Game Files" tip.

To do that, Right click the game -> Properties -> Installed Files

 

As far as the game seeming dead, there's not been a major update in a while, and they haven't really hyped up any upcoming release for DDA.  DD2 is still getting new stuff, but I believe they are focusing DDA development to finishing up some of the Kickstarter rewards.  They are also working on DD Next, which is a new game that is supposedly going to be for mobile devices.

Do you know where else there are save files of DDA other than the normal Steam ones? I've already tried verifying the files, tried deleting them and re-installing them, tried updating my graphics driver. Nothing has worked so far. I think most likely there are some hidden files installed in another location but I'm not sure where that is.

I'm almost positive your issue is that the firewall is preventing the game from working.

Check your firewall, anticheat, antivirus, antimalware, any program you have as it may be the culprit.

Also for better and faster responses to issues you should grab discord and join the server where people are most active - even if the game itself is dead with single digit number of players atm (Discord: https://discord.com/invite/dd2 )