This is a challenged based on a sim that I absent-mindedly made while playing my Buid a City 'hood. Basically, this Sim was a hermit.

To start out on this challenge build a small lot that looks like a cabin, preferably away from the rest of the neighborhood. I just moved that one cabin from Pleasantview to my town, but you're free to do what you like.
Alright, then you make your sim, They can look however you like. Their personality, however, has to be shy, so zero outgoing points, the rest of the points can be distributed as you see fit. Your sim can have a dog.
Now- to the important stuff.
Your hermit can not know anyone, unless your going for a certain achievment (see below) any thing in their relationship panel, aside from the dog, goes against their points. Your hermit can not visit community lots, so it would be a good idea to get a pond or garden. Your hermit can't have any electronics, or things that "convolutin' present folk" have, meaning no sports games, excersise machines or Decorations, either.
NOW onto points

1 point for starting off.
-10 for every person in the relationship panel
-10 each time your hermit goes into the front yard (excluding when they first move in)(to pay bills delete the mailbox, or download the automatic bill payer from Simwardrobe)
-10 for each time someone wanders into your hermits yard
-INSTANT LOSS if you start a positive relationship of any kind.

ACHIEVeMENTS

Grouchy old man- your hermit does negative interactions to anyone who passes his house- Ignore the relationship related point losses for every enemy he makes. 100 bonus points
Crazy Hermit- Kill every Sim that passes by (download a sim killing item, or become an evil witch) 50 bonus points
Friend to nature- Befriend all animals that pass by and become a Plantsim- ignore RP point loss for all animals- 120 bonus points
Green-thumbed Hermit- Max Gardening badge- 200 bonus points
Reelhaulin' Recluse- Max Fishing Badge- 200 Bonus points
Master Chef Shut-in- Cook every recipe- 50 bonus points
Mysterious Nice Guy- Become a Light witch (Ignore Relationship pointloss for the High-witch) And cast Benemoodious Simis on everyone who walks by- 50 bonus points.

50 bonus points for each maxed out skill. And 100 points for maxing out every skill.

So, tell me if you like this Challenge, and be sure to post a story of your exploits.

If we lose 10 points for going into the front yard, how do we pay our bills?

Use move_objects on to delete the mailbox. No more bills

Never tried this with TS2, but with TS1 this meant no more visitors. That would mean no chance for bonus/penalty points.

Question: When visiting a community lot is forbidden, how should the sim become a Light Witch/Wizard? I only saw the head witches at community lots and invited by sims who've met them before.

I deleted mine, and I still get an occasional odd townie. Only get like 1 human visitor per 1-2 days though (I do get at least 1-2 pet visitors per evening/night though)

Maybe I don't get many visitors because I'm using an island neighborhood

The High-witches can visit home lots, it's just VERY rare. Otherwise the "no witches on community lots" hack over at simwardrobe would make becoming a witch impossible. Also, to pay bills without going into the front yard, you could download the automatic rent and bill payer at Simwardrobe, simple.
I've edited the first post of arbitrary rules (only a big dog? Don't know what made me put that)

Alright -- So I did this, and the lady hermit pretty much went on a nervous breakdown after her dog died.

I made her open up a hair-salon so she could mend her problems by gossiping about the rumors in Pleasantview.