I very much appreciate rethinking the forum structure. This motivates me to be more active. :-)
The current tag system looks better now. I believe these categories can stay, even if it might be incomplete. The community is small right now, so adding too many tags at the beginning might also be a mistake. But when it grows, new tags can be added based on actual need. E.g. if a lot of threads show up about a similar topic but they have awkward tags, that's a good sign new tags are needed.
It's fine if it isn't perfect right from the start.
I suggest in the left sidebar, the full tag list is shown, not just an abridged one. There is enough space and having a full list removes an annoying extra click.
I suggest to remove the "Voxel" tag because that's not really saying much about the game. It's not a game genre in itself, it's only only a style choice so has almost no implications about the gameplay and only a small minority of games fit into it. It's too specialized. All Minetest game would automatically fall into Voxel anyway, so this tag is extremely redundant. I suggest to add "Sandbox" instead.
I suggest to rename "Code Q&A" to "Programming". Because "Code Q&A" is too narrow and limits the scope to a mere support forum. But it makes sense to broaden the scope to all programming-related topics, not just support questions. And de-facto, it's already used that way: Many topics there are not questions.
The description of the News tag looks like a mistake: "Blog & Planet discussions" doesn't seem to be correctl, it seems to me what you intended to make is an announcements forum, is this correct?
I'm not really happy with the "libre" tag. Don't get me wrong, I'm agressively pro-libre and free software. However, the existence of this tag implies that any game posted without this tag isn't libre. Thus, this forum would perpetuate the notion of proprietary being the norm. This isn't good. Also, it's very easy to forget the tag.
Frankly, I don't think this forum should be abused to blatanly promote proprietary software.
Also, it creates a practical problem: Forgetting the tag. I wanna bet a sizable portion of games under Projects actually does qualify as libre. It is unlikely the authors will fix it now. I feel its more practical to mention the libre/non-libre status in the thread as well.
(also, the CC icon makes no sense either because Creative Commons includes non-free licenses)