I have a list of all my games using pagination. It works great: http://www.colorcomputergames.com/games
However, I'd like to add links at the top of the page like: A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z
And so I want to be able to click on any letter and display only entries starting with that letter.
I was was going to make a template for every page but that seems inefficient.
How should I tackle this?
First, you should create a dynamic route (something like "games/glossary/<slug>") and point it to a template. A dynamic route means you won't have to create a template for every letter. Note the use of the <slug> token, which – although not entirely semantic – should do nicely in this case.
In your template, you'll need to pull the letter from the URL. Note that it's also a good idea to test if the variable is a single character, and in the a-z range (i.e. a valid letter, and not some other entity).
{% set letter = slug is defined and slug|length == 1 and slug matches '/^[a-z]/i' ? slug %}
If there is no valid letter in the slug variable, it's a good idea to throw a 404:
{% if not letter %}
{% exit 404 %}
{% endif %}
Next, you can actually use search syntax for the title parameter (specifically, a wildcard *), in order to pull all entries with a title starting with the relevant letter:
{% set entries = craft.entries.section('games').title(letter~'*').limit(null).order('title asc') %}
If you want to throw a 404 whenever there aren't any entries for any given letter, it's simply a matter of testing the length property for entries:
{% if not entries|length %}
{% exit 404 %}
{% endif %}
If you need pagination in your template, it'll work out of the box as usual:
{% paginate craft.entries.section('games').title(letter~'*').limit(10).order('title asc') as pageInfo, pageEntries %}
{% if not pageEntries|length %}
{% exit 404 %}
{% endif %}
{% for entry in pageEntries %}
...
