Hammerwatch is on sale, so maybe this is a good time to get some attention to the fact that it's out of date on GOG. While Steam has version 1.31, GOG is still on 1.3. Not only does this mean that stuff from that update is missing, most notably in my opinion the increased auto-fire speed, but it also means that online play between GOG and Steam versions is not possible. The 1.31 update was released on Steam in April, yet GOG still doesn't have it. I tried to contact the developers about this a couple of months ago, but they never responded.

Hm, I'll ping 'em about this too. I rather liked the game, especially the desert campaign.

Even worse.
Linux version is 1.23.

and because of that it has no Hammerwatch Expansion (v1.3 - Sept 2014), but at least we now have shiny pictures bundled with our linux installer. YEAH!

Steam is 1.31? So even Humble is behind - I have 1.30. Tch.

---Will update later

https://www.youtube.com/watch?v=PuZ24VBrbO4

That's not accurate at all. True, the 1.31 patch didn't do a whole lot, but increasing the auto-fire speed is vital. Without that speed increase, you pretty much have to button mash through the entire game because of how slow auto-fire is compared to button mashing. With the speed increase, the game is far more playable because button mashing stops being necessary. Plus, and I'm surprised the devs don't realize this, as mentioned previously the discrepancy has broken multiplayer between GOG and Steam versions.

In any case, I'm curious as to why the developer wouldn't just update the GOG version regardless. It just seems like common sense to keep your game updated to the same version everywhere that you sell it.

Yep, agreed. There were many complaints about the button mashing and also concerns for health risks, such as wrist pain too. Like I said the Steam version is DRM-Free.