As I recall, Creatures and it's related games are Windows 3.1 games. Not that that matters much, but Dosbox would run windows 3.1 (I know an easy source to get it too for certain old games to run seamlessly. not like MS is trying to protect that old GUI).

Still, you MIGHT (bit might) get it to work with WINE, assuming there's a port of WINE for Chrome OS.

Another possible option assuming you can get VirtualBox working on ChromeOS, is to install something like a lightweight Windows XP and run it from there.

If OP goes to a normal that won't be a problem.
And installing an OS isn't that much effort, all you have to do is make a bootable USB, shut down and boot into the USB.
All of these should be described into a step by step tutorial so OP won't have too much trouble doing this.

you are over estimating some people
even with step by step tutorials some people wont be able to figure out what to do

not to insult the op but he bought a windows game and assumed it would work on chrome os
and your having him install linux ?
i think you are over estimating his computer savvy

According to MobyGames, the first Creatures game had both a Windows 3.x and Windows (Win32, I presume) versions, while the later games were all Windows (Win32) games.

To my understanding, pure Win3.x (16bit?) programs wouldn't run at all on modern 64bit Windowses, unless, indeed, they were somehow running through DOSBox which is running Windows 3.x... So I am quite sure the GOG versions are Win32 versions of the games.

Google this: How to Run Windows Software on a Chromebook
Thing is you need Crouton to install Linux on Chromebook.
On which you will have to install Wine.

I'm pretty sure windows won't even run on a chrome OS laptop so Linux is pretty much the only choice there is.
Although he can try and install windows but that's really hard, costs money and probably won't even run.
And installing an .exe file in Linux is as simple as double clicking it like in windows (if wine is installed).
If wine isn't installed, just open the software manager search for wine and click install.

I agree the solution might be hard for non tech savvy users, but its possible.
If OP is determined enough to solve the problem and install the game it won't be a problem.

On the other hand, ChromeOS recently got an update to be able to run Android appkications, and thus --if it's an Intel machine, which many seem to be in my experience-- it can run Crossover for Android which Codeweavers recently released a preview of. Likely an easier setup than pure Wine.

Look again, the latest and greatest Mint (Mint 18, released last month) is Ubuntu 16.04. They have a new "branch" that is Debian based and future versions will come from that, but it is still currently Ubuntu.
I had no idea CrossOver had released an Android version (gonna have to check that out). That would be far simpler than pretty much any solution offered here so far, assuming it is stable enough already.

I didn't know that, that's cool.
Although I prefer wine I agree that crossover should be a better solution in this scenario.

It's okay as I have a windows 7 desktop but it's just a bit of a downer. Thank you for you message Chrome OS is just a bit rubbish really. :-)

Chrome OS machines can barely be considered as electronic toys, and you are trying to run a "computer program" by using a child's toy.

Wrong tool, wrong question.