There is a workaround to get the game to launch through Steam library while still using a taskbar link, but it requires a few steps.
First, create a desktop shortcut (looks like you’ve already done this). This functions as a url that will open the game through the Steam app, which functions the same as launching the game from within Steam Library. Works, as noted. But you can’t pin this directly to the taskbar.
Next, pin the app to the taskbar like you normally would - locate the exe in the game folder, drag it directly to the task bar or right click/pin to taskbar while it is open. Looks like you have already done this part as well.
So now the crucial step… once it is pinned, right click the item in the task bar, select GemsOfWar, right click again, and select properties. You now need to edit the shortcut, so go to the Shortcut tab. Right now, it should be pointing directly at the exe in the game folder. Instead, we are going to redirect it to open the url sitting on the desktop. So in the box marked “Target”, put in the full path for the desktop shortcut.
That path should be:
“C:\Users\xx\Desktop\Gems of War.url”
Where xx is your user name, and C: is your primary drive.
Should look like this:
(Your steamlibrary is probably on C drive, thats fine, you don’t want to change the “Start in” field from what you had)
Optionally, you may now use Change Icon and navigate to the original Gems of War exe in the game folder to ensure that you get the correct icon on the taskbar while the game is closed.
I distinctly remember this was an issue some time in the past, though I don’t recall the “instance already running” being the error message, a while back, if you attempted to launch the exe directly either through the game folder or a normal pinned shortcut, it would fail in some way (see possibly: 3.0.5 Known Issues (PC/Mobile), hard fail for some apparently, for myself I just couldn’t get the steam overlay). To my knowledge, this was fixed somewhere along the line, possibly in PC/Mobile: 3.1 Patch Notes (line referring to “Server Status will no longer glitch” maybe?, can’t see any reports of this specific problem after this point until now). I’ve been using the redirected shortcut workaround since it was originally an issue and it has consistently worked for me. Main downside is the icon disappears sometimes and needs to be reset (usually after an update), but the link itself persists and should never have to be redone since it opens via Steam.