Has anyone else managed to run a game that needs a PLAY disc in the optical drive, without an optical disc peripheral? (I have no optical drive on my current computer.)

To explain: I have games that require the "play" disc to be located by the game in order to authenticate it, which is required to proceed to play.*

Windoze 10 allows the mounting of a disc image (ISO) and the allocation of a drive letter to it.

The steps to create a working game are:
1. create an image (ISO);
2. create a virtual drive (a chunk of harddrive, with a partition extention *.VHD; the *.VHDX extention allows for more features, like expanding capacity, which are not necessary for a read-only game disc);
3. copy the image onto the virtual drive;
4. install the game (input the serial number supplied with the retail purchase) using the image;
5. run the game, which will check to see that the disc is available and authenticate with it.

So, I have managed to complete every step —— except the last.

When I run the game it complains the disc is not in the drive.

I cannot select the Windoze-mounted partition in the BIOS boot sequence (because it doesn't exist outside of windows, presumably) and I cannot tell Windoze to add the mounted virtual disc in the path for the authentication process.
I have tried to configure the BIOS. There doesn't appear to be any way to configure the boot sequence.
I have tried executing MSCONFIG to adjust the boot order via the System Configuration panel. There is only one option, the Windoze partition.
I have downloaded NeoSmart Technology's EasyBCD, but it looks to replicate the functionality of the System Configuration panel.

I have generously allocated some highly valuable prestige reputation for this meagre question in the hopes of encouraging altruistic contributions from the good folk who habituate this forum, which I will gladly award to the best response.**

Troubleshooting ideas:
I have used a standard bootable ISO image as a ghost for the Play Disc. There are images that do not boot, and that use the UDF protocol. Perhaps this might be relevant?
I could also buy an external optical drive. Or a USB cable to connect my DVD player as one. Both of these solutions are interesting but would cost more than the game.

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* For those overcome with ethical apoplexy, please remain calm. Gog does not sell Rome—Total War, otherwise I would buy it.
** I do, however, reserve the right to withhold my precious Rep bounty if I disdain all contributions. So there.

Does the error occur when you use a 3rd party utility instead of W10's own mount, eg, Virtual Clone Drive:-
https://www.elby.ch/en/products/vcd.html

If all else fails, I don't think anyone's going to do anything if you source a No-CD (the ultimate fix) for legally owned games. EasyBCD is a boot loader editor (used for editing the boot menu if you're dual-booting, etc). You need a virtual optical drive utility like Virtual Clone Drive (or as Paladin181 mentioned Daemon Tools). Something that actually makes an optical drive appear in Windows Explorer as if it were a real DVD-ROM drive. It should mount the ISO directly without messing about with Microsoft's .VHD files. You also shouldn't even need to touch the BIOS, MSCONFIG, HDD partitions or boot order at all.

Yeah, it's an ISO of the play disc. (That would be a noob error for sure!)
Actually the game I'm testing only has the one (DVD) disc. As I mentioned, I was unsure if I should make it with +UDF, or if it mattered if the disc was a bootable one, or if it doesn't matters.

This is the Daemon Tools you mean? It seems to be not-free. :(

Which game? Your only option may be to find a NO-CD patch

Daemon tools has a copy protect subsystem you could use. Haven’t looked at it in years though. There are other iso loaders, some with copy protect subsystems.
Me, I did this process many years back, ripped all discs to drive, but I got new exes, game copy world is one useful resource so long as you down the product, the patches there remove the disc need. Beware however, have a really good av, download to a separate machine and scan the files thoroughly, I don’t generally trust websites, but those types especially not.

You can also get a lot old games on various drm stores. Fireflower games, itch, gog, some on humble, zoomplatform etc.

A final possible, for some older games you can get engine replacements and such like. GZDoom for instance, so that’s another possibility.

I'm not proficient in pirate, so I'm not sure where I'd find such a magical device. Aha. That looks just the ticket. I'll try that and report back. :)

Daemon tools lite 10 is free, or you can pay. The free version, I blieve is limiited, but if you're not using it for anything more than mounting virtual disc drives, then you're fine.
EDIT: The free version has ads. Don't know if that's a consolation you're willing to make.

Auf Englisch, bitte?

Use VirtualDVD. It's free.

http://ohsoft.net/eng/vdvd/download.php?cate=1003

Also, if the DRM detects a false/copy disc, you will have to use a crack.

Crack is by far the easiest solution (call it No-CD patch if you own the game legally).

Or just mount it in Daemon Tools (thing I use for mounting ISOs).

I guess that there were already mentioned the best solutions (like "no-cd patch"), rest is highly depending on the game, but basing on my experience:

a)Sometimes, there is a config file inside game's folder (or one of its sub-folder), which is also containg your "optic drive" directory. Modification of it in some (single, sadly) cases can help in "seeing" your mounted CD image by the game.

b)There are some unofficial patches (quite often adjusting game to more modern systems, but not only), which are also "removing" necessity to have disc in your drive.

If you ever need one, buying an external USB DVD(-RW) costs peanuts. I bought one after I replaced my laptop's internal broken DVD-RW drive with a (third) HDD. I use the optical drive so rarely that it is fully fine to me to use an external one.

However, I think Windows 10 has issues with some widely used CD copy protections (SecuROM etc.?) even if you have the original disc, so most probably you still need to apply some kind of noCD crack.

Unfortunately, Virtual Clone Drive fails to execute. I suspect this is because Microsoft has specifically prohibited the execution (by rule, in other words they have explicitly forbidden the program) or, more likely, (my) Windows 10 installation uses UEFI. I must apologize in two parts: Firstly, my reading comprehension let us all down, because there was indeed a free trial version of the Daemon Tools software. I have downloaded the trial and it executes.

It does, unfortunately, advise that most of its features do not work with the UEFI format. (Shock!)

So I will need to re-format the hardrive with BIOS to test it … which is something that, if I do it, I shan't be doing it anytime soon. (!)

And secondly, on reflection, you may very well have won Tonight's exciting Star Prize* !!!1! Well, specifically I am investigating for Rome—Total War, since it isn't available on Gog.** Thank you for the abundance of options. :)

I see you had the same idea I was toying with, before I encountered Gog, to make a virtual jukebox (since an actual computer jukebox multi-optical disc storage system would cost more than every game on Gog at full retail).

I am pretty leery of websites with a piratical tinge. I have seen the virtual ecosystem that surrounds such interweb nodes, and they are like a crocodile buffet at the rainy-season migrating wildebeast river crossing. I'll check out some of the other stores, too.
Thanks. I'll check it out. :)
Yeah, I was also considering testing our DVD player (which has a USB connector) to see if it would do the job, but I need to buy a new USB connector cable (which I will probably do this week). If it works then I can pick up an external drive for under fifty dollars (ah, the tyranny of distance! —— the Antipodes are at the mercy of organized distribution larceny, courtesy of the oligopolistic practices of cartage companies).

Of course, this is the problem with DRM. Even with a legitimate copy I cannot play the game because of other configuration limitations. >_<

Thanks to everyone who has replied (some with repetitious advise that obviates direct response).

I'll have a bit of a play around and report back later. (I have lots of RL complications at present, so not a lot of time for games. ):

________
* A blow on the head? (I'm offering you a poke in the eye!)
** I am, however, testing my old copy of Neverwinter Nights 2.