If Riddler was to be correctly formed with the illness of OCD, then I'd see him being so far different to what we're used to, you probably wouldn't recognise him - at least at first.
The way I see it, as I try to with many characters, is that Riddler should go through a metamorphosis in his villainy. Riddler especially, as his illness can make him go off the rails if he's pushed.
This would be my interpretation of it:
You start him out as a complete and utter mystery. We know nothing about him other than that he's a threat to Gotham. He's contained inside his own little world which he never leaves. Could be a hideout or the sanctity of his own home. I'd prefer it to be his own home as it would fit into the theme of his illness: obsession. Let's say, because of his many hustling and bustling crimes over the years, he's managed to obtain a lot of loot; things ranging from millions in cash, to luxurious and rare items.
But the latter of that is never seen...as whatever he obtains, he just hoards them in his bedroom - the centre of his lair.
As the way I can imagine him being is of two worlds, which is also a mirror to Bruce/Batman and the obsessions he holds near to his own heart.
So in Edward's domain, he has items relating to his troubled past and crime-centered future. All of this in relation to his obsession about being the best at his skills. Never has he lost a game or a challenge thanks to his father's forceful encouragement.
However, every crime he has comitted is a cyber-crimes. He never ventures outside his home to commit his crimes. You walk inside his luxury apartment in a penthouse in Gotham or somewhere and you will never see a cleaner or neater enviroment anywhere else. Like Edward, in his impeccably smart green suits he parades around in on a daily basis, you'll never encounter a cleaner or tidier gentleman.
(And most of the apartment is kitted with something green. You'd see the colour in every shot - less commenly along with purple and injections of gold)
Couple that with a hint of eccentricity that Edward's so desperately trying to contain - fighting back against his intrusive thoughts in a situation requiring normality - you've got yourself a very unsettling nut on your hands.
Then, as prior engagements need attending, Edward slips out of the sharp, tailored suit and dons an outfit referencing the man he truly is underneath: an obsessed freak. In his lair, his personal sanctuary, he can reign free to his inner-thoughts and emotions, he can let loose. The smart suits are for outside purposes - the casual Riddler clothes he wears inside that room are dirty and marked over, contrasting against the state of his room - an extension from the state of his mind.
So you'd get something akin to the comics and the Arkham universe.
He starts out fairly innocent. No previous committed murders. But as Batman comes onto the scene - Riddler starts to challenge every aspect of his skills - including Batman's dedication to preventing death.
No domino mask either. Just a pair of thick, purple framed glasses.