cose_vecchie: On isthereanydeal.com you can set alerts for the games you're interested in: you can specify which stores to track and the maximum price (or minimum price cut) needed to trigger the notification. Of course you have to be comfortable opening an account there.
Undertale Blackwood Crossing ITAD is a good tool, but it does only part of the functionality I wanted.
I was imagining that, if a game is almost never on sale but now it is, maybe I should give it a bit deeper look just in case it is a gem that wasn't really in my radar. Losing the chance at the then current sale might lead to a few years' wait, or never getting the hidden gem at all. Magog allowed me to look at the whole catalog by order of how long it went without a discount. I could easily check
ALL games that were above the 1-year mark, especially if I filtered out games already in my library and those I tagged "Not Interested".
Still, ITAD is not a bad idea for specific games I am already interested in. I never thought to use it with these games that never go on sale in mind. Thanks for pointing it out.