Many people reading this will be at the start of their board game design careers. I know that, because most designers quit the hobby relatively quickly. Almost everyone is a beginner.
Some people stick with it, however.
They've been through the first-game epic monstrosity phase. They've been through multiple failed and abandoned projects. They might have a published game, or some small success. They have a career to look back on. They can now clearly see the mistakes they made, that everyone seemingly has to go through.
I'm in this position.
As I write this, I'm working on my 25th game. However, it will be only my third publishable game.
I look back on my board game design career, and there are half-made games, failed ideas, and prototypes, that I still want to make work.
What's the sensible approach to such projects?
Proper game design takes a huge amount of time. Time spent resurrecting an old project is time taken away from a new, potentially-great project.
When I look back at my past projects, I have games at all stages of completion. Some were even completed games that were proposed to publishers, and rejected.
If I'm going to resurrect an old project, I want to consider all the following:
Was this project complete (or almost complete)? If not, it's simply not worth putting the time into. Finishing it off and then polishing it to the nth degree would take 100+ revisions. I can spend that time making a new game.
What changes does the game need? If it's basically a publishable game, that needs some icing, that's fine. If it was completed, but needs to be reworked, it's effectively an incomplete game, as above.
How long ago did I last work on this game? Don't go back to abandoned projects quickly. Make five other games, and then come back. Your skill and perspective will have advanced significantly, and you'll be able to see some of the mistakes you made the first time.
Was there ever really a market for this game? If the game's mechanics have become dated or overused, or the theme was ill-conceived, it's better to just let the game sit on your shelf. Many people's early games are giant games, with high numbers of components. These games are not unpublishable, but you need to be realistic, and perhaps leave this game on the shelf, too.
Some things I resurrect are not games — they are themes, mechanics, or game ideas. When I resurrect such things, I do it as an entirely new project. I never resume where I left off.
Starting a new project is fun, which is very important for motivation. Fixing a broken game is a slog, and I'll just run into the same problems again. I may glance over the old game, but I really want the new game to be unpolluted by the old one. I'll steal its icons, and maybe a few card names, but that's it. If the new project starts looking successful, I'll then go back and mine all the little good ideas out of the old game, and try them out in the new game. Some were actually great ideas, just let down by a game that didn't work for other reasons.
In general, I recommend not resurrecting games. Don't be sentimental. You already failed at the task once, and now you're trying again. I have most certainly failed a second time at the same project. Once you've made twenty games, then go back and resurrect the absolute best one or two. Early on, just keep trying out new ideas, and learning. You're not a good enough designer yet, and there's lots of stuff you just can't do.
If you resurrect a game, it should be an amazing one. There were all kinds of good ideas I tried. Good is not good enough.