Aside from the tag system, probably the best you can do is use the advanced search to include or exclude particular authoring systems. For example, you can include Twine, exclude Inform, and so on. IFDB doesn’t have a built-in field for parser or choice.
You can also use the advanced search to exclude a certain tag (like parser). But you will still find some parsers in the results, since not all parsers are tagged with it.
Is it possible to search for multiple tags at once and maybe with an OR operator? Like, Can I search for games tagged with “twine” or “choicescript” and get both results together? How would I type that into the search field?
and that catches most of them. If I’m getting a lot of quest, adrift, or hugo games I exclude them, too. If you’re trying to count all choice-based games then you’re probably in trouble because there are so many parser systems, but doing published:2011- would exclude all retro games like The Quill, while including most of the earliest Choice-based games (like The Play in 2011).