Hi guys!
This is a visual novel/achievement spam game, which had originally 1000 achievements and in the end of February, 2018 had 4000 achievements added.
As with all the other Unity-based achievement spam games, it could present some problems due to the changes and so on.
The game was launched in January, 2018 so you can have two kind of problems:
1- You bought and got it right away, and got all the 1000 achievements popping up normally while browsing through the game or leaving it idle in tray or on screen, so that now with the new achievements you don't see them popping up and you're stuck at 1000, or more.
2- Simply, you installed it before or you have some issues and for some reason the achievements stopped opening.

Well, you've got to follow a simple procedure that's quite always the same one, with small differences related to the folders.
1- uninstall completely the game through your steam client/library
2- go on alt+r and type regedit, or open your registry editor in any way you please (start, run, type regedit or search regedit and so on)
3- follow these routes, starting from Computer \ HKEY_CURRENT_USER \ Software \ DefaultCompany
4- when you're here, delete the whole "dad's co worker" folder
5- to be sure everything's been deleted, you can search for defaultcompany or dad's co-worker, in your steam folder or type %appdata% and go to locallow: if there's still a folder called defaultcompany and containing dad's co-worker, delete everything related with this game
6- re-install it

Then, DON'T run it in tray - it seems for some reason (but I'll edit if I'll have other evidences) that the game's sound and so on keeps on running even in background, but the achievement timer isn't counting/going up. So, idle with the game open. You just have to pick new game and let it idle, there's no need to progress through the story - the achievements are the same spam of other 1000 games on Steam, so they're related only to the seconds spent in game. To be sure, don't browse anything with the PC you're using for this thing, but let it idle on the main screen.

IF and only if you already played the whole thing a month ago, or you have already hours idled on your game, the timer will re-start from zero and of course it won't re-unlock the achievements ranging 1 to 1000 so you'll have to wait around two hours for the timer to start going on again; after 120 minutes or such, it will have surpassed the 1000 mark and so it will start running towards the 5000th one.

So far, I didn't receive feedback of broken achievements - they unlock perfectly as you idle until the 5000th one. In any case, you're forced to wait since I don't think there's a way to know at which point the timer in-game is; some achievement spam games add a timer in-game but this is not the case, so just let it idle after having deleted everything as I said from the registry (regedit) and the Steam/steamapps/appdata folders.

Just for info, it took me a total of 8 hours to get them all but I think this varies from player to player, especially if you idled already for many hours before the new achievements were added. I left it a whole day idling offline and it started re-popping after three hours I think, anyways, sometimes before I went away leaving the laptop idling alone. Then as all the other achievement spam games it unlocks one per second or such I think, the first 1000 plus the first new ones were like this, then I left it here for an entire afternoon. Too bad there are no timers at all, but anyways, this is it xD

Good luck!