Well, nothing as cool as that comes to mind, but:
- Wizardry 6 and 7 used the PC Speaker for digitized sound effects that were good for their time.
- The Dungeon Master games had PC Speaker music at the beginning, possibly MOD-like
- Barbarian II (aka Axe of Rage?) had a catchy, multi-voice song that played while waiting for the user to pick a gender for the player character

I also had a fancy graphical DOS-based MOD player in the early 90s that supported the PC speaker as an output device (among others).

One problem with using the PC Speaker as a digitized sound effect output device is that it was a 1-bit DAC. In other words, the speaker cone is either at rest or extended. For simple tone-based music, games would use timer interrupts to vibrate the speaker at various frequencies, but for digited sound samples a game would have to actively push bits of data at the speaker because there was no buffering or DMA mechanism available for doing that (it just wasn't designed for it). As a result, the CPU would have to be totally dedicated to driving the speaker to reproduce a sound, and you can see this in a lot of old games (the game pretty much sits there doing nothing but playing the sound, either until the sound finishes or until a couple seconds after the user hits a key).

Well there are games providing animation and digitized speaker sound. I guess they are relying on a pretty strong 286 CPU to provide fluid gameplay while playing sounds over the speaker. Links for example has this classic intro sequence with a small video-like animation which was very cool back then.

Star Control 2 really seems to be the pinnacle of this development since it features continous, fast paced action while delivering a soundtrack with channel mixing. It's too bad I didn't have the game "back in the day" because I had no soundcard and I certainly would've been amazed by the game. (Which is also incredibly funny. For those who have never played it - give it a try since it's arguably one of the best games produced in 1992.)

Btw, HunterZ, do you still have that mod-player? If not, do you know it's name?

No, I don't think I have the MOD player, but I think it was called something like WOWII. I just found an old floppy labeled MOD STUFF, but it only has MODEDIT v2.00 and MODPLAY PRO v2.09B - both of which are text-mode programs (the first is a tracker and the second a simple player).

There are many MOD trackers/players that support PC speaker output, but most of them only run on a 386 or better 😖
Simple DACs on the printer port also were common back then, the CPU load was still quite high, but the sound was much better (even better than plain SoundBlaster in some cases).

Ever heard SC2 on a GUS? 😁

Though I own a GUS clone, I have only listened to it with Dosbox emulation. But this should be pretty close since it's only digital sound.

I only heard of printer port DACS recently and they had virtually no gaming support. There are about three games in the mobygames database which support it.

Disney Sound Source and Covox Speech Thing were parallel port DACs.

We had a Disney Sound Source back in the days, damn that brings back memories. Although our first PC was almost a beast compared to your 286; 486SX 25MHz, 2MB RAM, 80MB HDD, those were the days.

I once had a Covox Soundmaster+. It was something like a mixture of AdLib card + parallel dac.

VisualPlayer can play MOD files through the PC speaker under DOS environment.

ftp://ftp.nsk.su/pub/msdos/sound/vp20.arj

ScreamTracker was pretty good at that, although it used different file format. There were other "trackers" but this is the one I remember.
Might&Magic III (Isles of Terra) had pretty impressive voice through PC speaker in the intro, well, it was more impressive than intelligible but still very cool.
A few Access games used library called RealSound -- Links, Mean Streats. IIRC, those required 386.
There were a few games that shipped with sound hardware. Leather Goddesses of Phobos II included "Lifesize Extender" -- parallel port DAC, similar to Covox.

Yeah, some older software can do that, (Megazeux 1.2 could play four-channel MODs over the speaker,) but the quality was generally lacking, and it didn't work with piezoelectric speakers (the kind used in laptops.) Still, though, it was an impressive achievement. I remember one demo program that played Obi-Wan Kenobi's "you cannot escape your destiny" line from "Return Of The Jedi."

vasyl, didn't ScreamTracker introduce the .S3M format? The standard MOD formats these days are MOD (Amiga/ProTracker?), S3M (Scream Tracker), XM (Fast Tracker 2?), and IT (Impulse Tracker).

I'm a tracker music fan... The IRC channel for modarchive.com was my hangout for a year or so while I was in college.

commodorejohn: I've noticed that piezo speakers are used in a lot of modern desktops too, as they're not useful for much else besides POST beeping these days. I used to have a MODEDIT/MODPLAY and a fancy graphical DOS mod player named something like WOWIIE that could all output via the PC speaker, but they sounded pretty bad because I had to run at something really low like 5000Hz on my 8MHz 286. Also, the PC speaker of course only supports 1-bit sampling because it only supports on/off when used as a DAC).

I also once came across some utilities and a schematic for making and using a sound digitizer board. It came with a recording of the author singing "Daisy, Daisy" (or whatever that old song is called). I tried to build the board (my dad was a professional electrical engineer at the time, so he was able to get me the parts and materials that weren't already laying around the house), but like most such projects I never managed to get it working.

Another time, I tried building a simple parallel DAC using some special chip and another schematic I found once, but it of course never worked either. I've more recently seen an intriguing schematic that pretty much uses only resistors, but the world has since moved on and there is little use for such things in the arena of video games now (even old ones thanks to DOSBox).

Yes, ScreamTracker used .S3M. Not the same as .MOD but conceptually very close. MODPLAY supported it but listening to it on Soundblaster was just not the same. Apparently, I had fairly decent speaker then. Now I don't even know if my PC has a speaker -- I never connected that wire to the motherboard. MSI boards have four boot diagnostic LEDs so I just don't need any beeps.