It's early days but I'm mixed about using github.
It's already approaching 100 suggestions and 90% aren't of interest to me personally, I did vote on ones I did find interesting! But gotta admit, it makes me lose hope that new suggestions will be seen (assuming Scirra only sort by thumbs up, but perhaps they will browse throughout). A new idea may appear, get a few votes, then disappear into the void if it didn't gain enough votes, only to be found if someone stumbles upon it or if they did a search with the right search terms.
Maybe would be good for a "trending" or "hot" sorting for suggestions that are getting sudden recent votes or comments, if github allows this? Maybe it exists already, bit new to this.
It may also be harder for new suggestions to thrive because it's not grouped afaik, where the old system could have "event sheet" category and can see top suggestions just for this - although this may not matter depending on how Scirra browse (I guess I imagine they might think "OK today, let's check out some event sheet suggestions", but maybe not). That's how I used to browse, I wouldn't browse areas of C3 I don't currently use, and would mostly browse categories I have an interest in.
Also without grouping, most people may not feel eager to browse randomly through a list of things they don't know about. I felt that way when browsing recently, just lots of stuff I didn't understand or didn't find interesting.
Imagine when it reaches 200 or 300 suggestions, is anyone able to genuinely tick "I checked if this exists already", would need to rely on a search (where you may use different terms and may mistakenly miss an existing suggestion), or alternatively, browse every page. The old system was manageable since categories made it easier/quicker to check if exists.
Wilson's point is curious, if people did have 1 suggestion at a time, would indeed help keep it manageable and everyone has to think carefully what they deem as important, which is what Scirra always hope people will do. I can't say I fully agree because I posted about 5 suggestions already, and all of them I'd love to see, but then it's interesting if I had to genuinely pick only 1, what would I pick? (prob would go with "custom icons" eheheh pls vote).
Although if limited to 1 suggestion... People could just make new accounts to post multiple suggestions. No way to win. But that was already a frowned upon issue with old system, where vote spamming from alt accounts could occur (tho I suppose this is catchable in github too if sudden unusual accounts appear).