Firstly, the games library sounds like a great idea. I would recommend using
APT as a base. It seems like it already has enough features to provide what
you suggest (with a bit of tweaking by the bit that serves it up, of course):
* screenshots: If the description used were replaced by an HTML-like
language, these could then be incorporated into it- or simply do it however
Add/Remove Software does it;
* data import: APT has the ability to add tags to packages, so this could be
done server-side and provided as part of the package metadata;
* search: doable with APT, using tags where necessary for specific features;
* reviews: Incorporated into the description;
* rating: Probably the only exception to this principle- could be performed
in a similar way to Add/Remove Software or what-not;
* hardware detection: Package key information as tags, and then simply have
the software filter for information which suits it- also has the advantage
that users can choose to look at games outside their specifications if they
want;
* links: Incorporate in the page description;
* payment: Incorporate in the page description
It should be noted that where I suggest "incorporate in the page
description", the implication is that the data will be stored in a format
which can then be parsed for display; it does not necessarily imply
text-readability.
As for time, I'm a little busy at the moment. However, with the obvious issue
that my ability to contribute is rather limited (for now), I'm certainly
willing. Is there anything specific I can do?