I wonder, how did anyone connect an MT-32 to their PC? I had, and still have, an MT-32, but it never occurred to me anyone thought of it as a PC accessory. I used it with all the rest of my MIDI stuff, which at one point included an XT, but I never used it the way most people did, apparently. I just used it as a really lousy-sounding MIDI synth.
The Roland MPU-401 was 'the original' in-PC add-on MIDI interface card but huge numbers of the Soundblaster / Soundblaster clone sound cards which included a 15-way sub-D 'game' port also implemented MIDI on two pins of that port. As far as software was concerned, this hardware also looked like a Roland MPU-401 MIDI interface. To make the MIDI fully operational an extra bit of plug-in hardware with an integral optocoupler, output driver and 5-pin DIN connectors was required.
If you have a PC with a 15-way sub-D game port on it, the chances are that it already almost has MIDI. Google 'game port MIDI cable' to find the other bit you need. If you like messing with electronics then this portion is not hard to make yourself, but since they rarely cost more than a few dollars / pounds / euros ready made, it is hardly worth it.
Owners of Atari ST computers were even luckier - they came with a fully functional MIDI interface, and a lot of Atari ST games did support the standalone MT-32.
Having said all that, the MT32 version was not always the best version of a game's soundtrack. I always thought the very best version of the DUNE (PC) soundtrack was the 'native' PC version that it played through the Soundblaster AWE64 that I had in that machine at the time. The MT32 version just wasn't as thick / rich.
In fact the MT32's sound generally was quite thin - but it was a nice novelty at the time, having up to eight instruments (one of them a sampled drum kit) playing simultaneously out of a little box like that. In fact the MT-32 could produce much better sounds than the stock sounds if you used a computer based editor to create and upload your own sounds - the better game soundtracks did just that and used the same capability to make the MT-32 play realistic custom sound effects not found in the MT32's stock set of sounds.
The real design flaw with the MT32 was that it did not have non-volatile 'patch' (sound definition) storage memory, so if you designed a new sound you had to save it off-module (typically to a computer) and then upload it back into the MT32 next time you powered it up.