For example, desired modifications would include:

- Alteration of its contents (add or remove games from the mix).

- Revision of the order (moving games up or down)

- Changing individual game descriptions or ratings (already submitted).

- Renaming GOGmix.

- Finally, deleting GOGmix.

Which of the above is possible?

All of the above are possible.

Quick responses! Thanks!

Another question:

Can I "mark as solution" multiple posts or this feature is limited to just one?

As both answers constitute a solution, I would like to be fair.

No, you can't. It has to be only one. And if you want to be fair, it should ideally be someone else entirely who just happened to be passing by.

[Inconspicuous whistling]

Přemysl, the Ploughman, would be proud.

LOL. Nice point of view!

It's a pity to have only one marked solution.

Of course in this particular thread, the "marked solution feature" doesn't have a pivotal role, but in other multi-pages topics or technical threads (with scattered useful information across many different posts) it would be extremely helpful to have this limitation revoked.

Anyway, I'm marking the most complete answer.