Disclaimer: these rules are designed for a character in a fantasy universe who has been totally blind for a very long time. They are intended to make the character viable in d20 mechanics, not to imitate real life.
The Blind PC Starting Package
1. Build your character as you would any other character.
2. Cross "Spot" off your skill list. You can't make Spot checks at all, period.
3. Skill checks that rely partially on vision (such as Search) can be made at no penalty whenever you can use your sense of touch, hearing, or some other sense to help you. Otherwise you cannot use these skills.
4. You have a +2 competence bonus on Listen checks. You don't have better hearing per se, you've simply learned to pay attention to nonvisual cues that the sighted don't notice.
5. When moving you have three options:
6. You are always flatfooted against enemies you cannot hear. Once you have heard an opponent you regain your dexterity bonus to AC.
7. You are immune to Gaze attacks and blindness effects.
8. You can still use any of your class abilities (sneak attack, favoured enemy bonuses, etc.) as normal. This bears repeating: you still get all your class abilities. Having been blind for years, you gained your class abilities as a blind person and you did not train to base their effectiveness on vision.
9. Do not apply any of the blindness/deafness penalties for being blind to your character; use only the above penalties.
10. Do not apply any of the Invisibility or Concealment bonuses to your enemies, except as noted in the Combat Guidelines below.
11. Take one bonus feat. If you ever permanently gain (or regain) normal vision, you do not gain your next feat.
Combat Guidelines
At the beginning of combat, you cannot attack any enemy until you have pinpointed its location. The best way to pinpoint is by using the Listen skill (see below). You can also try to pinpoint by making a touch attack into two adjacent 5 foot squares. The touch attack is against the touch AC of any creatures in the squares and has a 50% miss chance rolled by the DM; if it succeeds those creatures are pinpointed. These rules are core and are found under the Invisibility rules.
At the beginning of the first round (and every round thereafter), take a Listen check as a free action to find out what enemies you are aware of or have pinpointed (Once you are aware of an enemy you remain aware without further listen checks; a pinpointed enemy must be pinpointed again, however, each time it moves). If you are unhappy with the result you may use a move action to try again in the same round, or wait and retry it as a free action next round. This rule is core, from the Listen skill section of the PHB.
Any creature who has successfully hit you or whom you have successfully hit is pinpointed until that creature moves. This applies to melee hits with a 5 foot reach only.
Your allies are always pinpointed for you, unless they specify otherwise. This is a house rule.
Once you have pinpointed an enemy you can attack it with a 50% miss chance. If you successfully grapple an enemy, that enemy does not have any kind of concealment from you while grappled.
Once you have pinpointed an enemy you can use Line of Sight spells against that enemy. This is a house rule.
Without pinpointing anyone you can pick a square at random to attack. We recommend rolling a d8 to determine which square you attack in melee and don't bother randomly attacking at long range. This way you avoid any metagaming.
The Listen Skill
As you can tell, Listen is a pretty important skill for a blind PC. In case you wonder just how much you can do with it, and how hard those checks might be, here's a handy guide.
There are two things you need to do with listen: be aware of your enemies so you aren't flat-footed, and pinpoint them so you can commence the daggering. You don't need to pinpoint an enemy to get your dex bonus to AC vs that enemy; you just need to hear them coming so you can put up your defences and start bobbing and weaving. That leads to two different levels of success on skill checks:
Full AC
To get your full AC against an enemy you just need to be aware the enemy is there. The listen check to be aware of an enemy automatically succeeds for enemies that are talking or fighting (the DC for the listen check is 0). This includes almost all enemies you'll face. If there are circumstantial penalties you might have to make the roll anyway but it will be easy to succeed.
If the enemies are trying to be sneaky, then use their Move Silently roll with any modifiers (armour check penalty, moving full speed, etc.) as the DC. Note that most enemies won't try to be sneaky in combat because they won't expect a blind person to be part of the PCs' party. Obviously, rogue- and ninja-types could be an exception.
Pinpointing
Pinpointing adds 20 to the DC of the the Listen check. So for talking/fighting enemies, the DC is 20. (0+20 = 20). For sneaky characters it is their Move Silently plus 20 plus/minus any circumstantial modifiers.
Defaults
Your DM probably doesn't want to make Move Silently checks for every monster every round, so we suggest your group just uses the default Listen DC modifiers. They boil down to:
+5 for armoured opponents moving at half speed (25 to pinpoint)
+10 for unarmoured opponents moving at half speed (30 to pinpoint)
+15 for low level rogues (35 to pinpoint) and more for higher level rogues.
+1 for every 10 feet of distance between you and the target.
The Drawbacks
If you use the Starting Package and follow the Combat Guidelines, you suffer exactly one drawback that other characters don't suffer: a 50% miss rate on certain attacks. That is the only real drawback.
The other alleged drawbacks, of course, are not knowing where to attack and being flatfooted some of the time. But those drawbacks don't exist if you make successful listen checks, which you will. You get to make two listen checks the first round! A first level blind character with max Listen ranks, the starting package, and a +1 WIS bonus has a +7 Listen skill. +10 if you have Skill Focus (Listen). Essentially this means you will make your listen checks, which means you are only flatfooted when ambushed and you are only unaware of enemies that are great at sneaking. In other words, you are exactly the same as every other PC out there.
That said, that 50% miss rate is a big hurdle. On physical attacks you will only hit half as many times as a sighted character of the same class does. Think carefully about whether this is going to be fun to play out.
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