I have made an initial version of the form interface for editing game pages. See Development:Forms for some sample pages to experiment with.
This is an initial version to demonstrate the viability of this approach. Let me know of any errors in the settings, e.g. dropdowns missing values that should be supported (or vice versa) or multi-instance templates not having the correct minimum/maximum use limit. The form layout is done with standard wiki tables, so any spacing issues etc. can be adjusted as needed.
The biggest change is that form editing works around all form content being contained within templates. Any text not used in a template parameter gets relocated to the bottom of the page (shown in the "debugging area" when editing with the form). The updated templates have notes sections etc. so information can be added in the usual places while now actually residing within the associated templates.
Another change is that pages edited with the form have empty template parameters and template whitespace removed (there is no option to disable this), so manual editing is not as easy to read as it was before.
This form introduces some new templates such as Patchbox. These templates provide a layout specific to that type of information and supply additional semantic data for the wiki. In the case of Patchbox, the Issues fixed/unresolved sections would link to the Patches section when it exists (this is implemented already but isn't visible in the examples due to using the development namespace).
Template features that rely on property checks (GOG.com and Steam Cloud rows, WSGF infobox icon, etc.) don't work in this namespace after a page has been saved.
Unfortunately, due to the way forms work each template can only be used in one place on the form (but multiple times in that place). This form uses redirects for several templates to get around this limitation (listed in the "Redirected templates" section).
This form currently has an issue where some page sections are shown when empty. This would be resolved with some template adjustments (most of which are already present). EDIT: form editing from section links on the page isn't present yet.
Anyway, let me know what you think.
EDIT: I have moved the sample pages to my user space (I didn't realise the Development: namespace had restricted editing). Feel free to tinker with the pages.