Q:What am I even talking about?
A:The texture filtering of Battlespire, by default has a mushy linear effect. Using this guide, provided it works for you, will give a filtering more resembling nearest filtering (more pixelated).

Before attempting this, try less hacky ways to get better filtering. Try editing the bs.conf file in the DOSbox directory within the Battlespire installation directory, changing the output and scaler values. If this does not work, then continue with this guide.

This is a bit of a "brute force" method, but I was unable to get it to work any other way. We will be changing the system's resolution, to that of Battlespire's.

I was able to get this working using Proton (5.13) and with Boxtron (native Dosbox).

You will need to install a resolution changing software, in this case I used xrandr. If xrandr is not supported on your system, you can try and adjust the following commands to match your system's equivalent.

In the Battlespire steam launch options, write the following command where <Device> is your monitor device and <Width>, and <Height> is your monitor's resolution:

xrandr --output <Device> --mode 640x480; %command%; xrandr --output <Device> --mode <Width>x<Height>

My command looks like this:
xrandr --output HDMI-A-0 --mode 640x480; %command%; xrandr --output HDMI-A-0 --mode 1360x768

In order the get <Device>, use the following command:
xrandr -q

When launching Battlespire, launch using the fullscreen option.

Sometimes when first launching Battlespire, the cursor will be unable to respond. If this happens simply quit out and restart Battlespire.

If your game crashes, it will most likely leave your system with a 640x480 resolution. This can be fixed with the same xrandr command:
xrandr --output <Device> --mode <Width>x<Height>

In may case the command is:
xrandr --output HDMI-A-0 --mode 1360x768

When attempting to record gameplay, obs failed to capture Battlespire. Instead I had to resort to Dosbox's native recording, which is, by default activated with left control + left alt + F5. This key combination is usually already in use, so I would recommend changing the key combination. I added a holding of left shift in addition to the other keys.

Before Implementation:
https://images.steamusercontent.com/ugc/14859159567372440702/9FDCF06DBC6EBCBAAE955F2CC3A55E405D32B97A/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

https://images.steamusercontent.com/ugc/14798667078640195652/D4CFD5C3514D05BCE9CF94F9AEE2AE3AB114D077/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

After Implemntation:
https://images.steamusercontent.com/ugc/13245776725360588282/316E45EB89A9C0F3E56A5DF998BABFE7AB4244D8/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

https://images.steamusercontent.com/ugc/15155116960887399523/E156C85A1A39968AE70CDFFFBEB94EBC64F20B04/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false