I thought I had more hours invested in Pathfinder: Wrath of the Righteous, but, after checking, I'm still 50 hrs behind your Shovel Knight Dig...
I think I have over 200 h on Witcher III
since I have 3 playthroughs
RdR 2 - 120 h
Mass effect series - probably like near 200 h also , played that multiple times throught the years
My most played game is Lineage 2, thousands of hours.
On steam I think this, berseria, yu-gi-oh and rising hell are my top played. A few hundred hours etc..
On Witcher 3 and Skyrim on PS4 are 300-400h each
But mafia 2 and snuoer elite 4 I might have played even longer xD
600 hours is insane?? Is there really that much content or was most of that idle time?
I remember playing the original Shovel Knight many years. I think it took me around 15 hours for a more or less completionist playthrough.
This is the time I have spent across runs and levels digging

~200h it was forgotten open and the rest is me in the menu doing stuff, buying stuff, checking stuff and playing with an owl in game xD
Shovel Knight Dig is nothing like the rest. You just.. Dig and defeat bosses at the end of the world. Plays like a rogue
The original games are platformers and I loved them even more. Beat them all and on NG+ but I don't think I can 100% those.. Not now anyway.. No patience xD
I remember when I bought Alpha Protocol DVD. I didn't really measure how much time I spent on it, but I remember I finished it 5 times in a row.
Mafia 2, Fable 2 and Sniper Elite 4 I have finished more than 20 times each tehehehe