So I'm absolutely starry eyed in love with this game, I've followed the development a while and pre-ordered on switch, I'll be picking it up on PC in the future too. The editor, my god, the editor is incredible. It feels like I could create as high quality a campaign as the official one. I got to thinking about what we didn't have for custom campaigns that the dev team did and I think one of benefits devs had is that (it seems) you wrote the voice lines to match some of the text -- obviously we can match these ourselves too but it could be a weird workflow. Anyhow, my suggestion would be to expand upon the available editor assets in future updates, small voice lines in particular to give even more freedom to people writing custom content. Perhaps just allowing non-commanders to use commander voice lines but with a pitch change could be a stop-gap solution. Expanding upon basic units in particular, maybe having a decorated/costume versions of them (maybe even just an edited portrait and not the sprite) so we could make recognisable story characters from non-commanders. Eg. Felheim Skeleton Soldier with an Eyepatch using Mercia's voicelines pitch changed. TL;DR The editor is amazing just keep adding more content to it in future updates when you can. I know this is a very asset heavy suggestion and might not be something you can approach for a while if your voice actors weren't in-house etc.
