Black mirror 2?

Not that one, either.

This game has two protagonists - both unsympathetic in their own way.

Sherlock Holmes vs Jack the Ripper!

Close!

Same country, same era, one character a criminal, the other an investigator.

Sherlock Holmes Versus Arsène Lupin (or Nemesis) ?

Different men. 

Maybe this helps?

   

Alter ego?

Bingo!

Bingo!

Hey Bob can you remind me? Is this the game that you had a couple of endings depending on what you do. I remember a fleeting scene in my mind where you had to secure a wheel on a ladder in a library or that's a different game? My mind is making circles, I think it was a game with a Latin name (not Memento Mori or In memoriam maybe alter ego, are there others?)

next:

Attached Files

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That’s the  freeware Kings Quest game from last year.