I dig tabletop/pen and paper RPGs, though without an irl group and living in an unusual timezone, I often don't get to actually play any. Usually, I just sift around to check out their mechanics a little bit, get a feel for fluff, and just run through chargen a bunch. I've managed to do a few forum RPs, but holy balls are they slow. They don't mesh very well with the sorts of games I have managed to get into, though - things like Paranoia and MaidRPG, where a lot of the fun is from coming up with shit or improving on the fly and stuff.
I kiiinda hate D&D - class-based systems and level-based systems are especially boring to chargen for, since it's often a big package deal with limited fiddlyness, where I can't pick and choose things that sound fun. Besides that, the dice mechanics are super goddamn random - d20s have a huge variance, and even if you sorta focus on a thing, even as a class that's good at it, you still probably have like a pretty hefty failure chance. The 'quadratic wizard/linear fighter power growth' thing is also a problem. The alignment system I never really had a problem with - until I realized it was used mechanically. 'The paladin can sense evil! Are you evil! That dude knowsss'. I originally just thought of it as just like a sorta descriptor you'd set yourself to quickly describe your character and help get into their mindset - 'Is he altruistic and heroic or a selfish dick? Does he believe in authorities or does he scream 'fuck tha police'?" and the like - but once you start tying it to mechanics it gets really dumb. Like, 'you are ABSOLUTELY EVIL. I know this because I used some wiggly magic stuff and it said 'yep, you're evil'.' I also may or may not try to read the entire bloody feat list every time I go to pick one whenever I try to run chargen. Have you seen those things? Pathfinder's is like three or four columns, fifteen page-downs long, of just the feat titles. About 3% of which are ACTUALLY take-able by my dude.
AD&D 2e gets a pass though. Its magic has side-effects, IIRC - like, Haste ages you a year or so if you get it cast on you, so it's a trade off between awesome stuff and that - and as I recall it's a lot more lethally designed for the player. No feats to optimize and agonize over either. Kinda clashes with my preferred method of chargen, I suppose, but the way it's built is consistent, at least.
I've never actually looked at Delta Green, though I am aware of the premise. I've never actually looked at it or CoC itself, actually. >.>
Probably my favorite experience in a not-forum-RP was a one-shot of All Flesh Must Be Eaten, over irc chat. I apparently followed an off-duty clown into a undefendable doughnut shop, smashed a window open when the horde came for us to flee, while said clown failed at hurling a coffee pot at my dome to knock me out as bait. He hid in a cupboard, and (due to not noticing his filthy betrayal) I looted the next building over and went back to save he with the only thing I could find - the lawyer's office's big ol' potted plant. I crushed like two undead pissants with that thing, before it broke up, it was glorious. I also managed to not die, despite being a black guy in a red shirt.
My favorite system I've ever read/seen/whatever is probably 7th Sea. It's dice mechanic is awesome - called 'roll and keep', you basically roll your stat/attribute + your skill, but only keep your stat's amount in dice, and compare that total to a Target Number - which can often be raised with, well, Raises, which account for more difficult things like targetting specific body parts, using a special technique, or just generally doing something awesome. You also can get free raises from, say, special sword style schooling or something, that make your stuff easier to do. Raises have to be declared, so you're intentionally raising the stakes of your rolls and stuff - really cool.
Besides that, the fluff and setting is super neat. Someone who hates fun might call it 'racist', because... well, it kinda is, I guess, but it's essentially a super-exaggerated Europe in the Age of Sail, with pirates and all kinds of stuff. Eisen, the Germany-analogue, is WAR-TORN and has AWESOME MAGIC STEEL; Avalon, the British-Isles-analogue, is ruled by a QUEEN, and is sorta-divided/tense with the Scottish, Irish, and Welsh analogue kingdoms that are technically under it's banner - there are also the FEY, who are mostly not statted for Lady of Pain-type reasons. Italian analogues have crazy fate-string seeing Fate Witches and are extremely mercantile, as are the Swedish/Norwegian analogues, who have a split between ye olde VIKING VIKING-types and ye new mercantile-trade-and-crafts types; I think France has Musketeers and is relatively big on it's army; Spain has the Spanish Inquisition, etc. Russia's in, too, but I don't know much about them. Magic is in, and tied to noble bloodlines for the most part - the Spanish's magic was LATIN FIRE before the Inquisition basically killed the royals. Vodacce - ye Italians - have aforementioned Fate strings and Tarot cards and such; Avalon has this thing where you basically channel old Legendary figures.
I could fangasm over it way more, but, ugh, I should probably wrap up.
Besides 7th Sea I also love Deadlands. Super Pulpy cowboys + spooky zombies and supernatural crap, some poker-mechanics to the system, such as wizards basically casting their spells via playing cards with the devil - with an actual poker deck -for MAXIMUM FLAVOR-IN-MECHANICS.