AD&D ability tests, streamlined

 As I've mentioned in my Hyperborea review (check it pout!), I really liked how the game tries to streamline AD&D ability checks: 

This is a simpler version of the (much more complex) original, which included percentile Strength (see OSRIC, for example):

TRENGTH	BONUS TO HIT	BONUS TO DAMAGE	ENCUMBRANCE ADJUSTMENT (IN LBS)	MINOR TESTS, E.G. FORCING DOORS (CHANCE ON D6)	MAJOR TESTS, E.G. BENDING BARS AND LIFTING PORTCULLIS (CHANCE ON D%)
3	-3	-1	-35	1	0
4-5	-2	-1	-25	1	0
6-7	-1	0	-15	1	0
8-9	0	0	0	1-2	1
10-11	0	0	0	1-2	2
12-13	0	0	+10	1-2	4
14-15	0	0	+20	1-2	7
16	0	+1	+35	1-3	10
17	+1	+1	+50	1-3	13
18	+1	+2	+75	1-3	16
18.01-18.50	+1	+3	+100	1-3	20
18.51-18.75	+2	+3	+125	1-4	25
18.76-18.90	+2	+4	+150	1-4	30
18.91-18.99	+2	+5	+200	1-4 (1 in 6 extraordinary success)	35
19	+3	+6	+300	1-5 (1 in 6 extraordinary success)	40

Although I like the simpler version I think it would be easier to go even simpler - while keeping vaguely similar chances.

Here is a simple formula:

- Ordinary ability checks: roll under ability.

- Extraordinary checks: roll under ability-10 if your ability is remarkable enough (13+, which is where you start getting modifiers), otherwise it is a % roll. 

Alternatively, just make a percentile roll with HALF you ability score if you want to keep things more similar to the original, or your whole ability if truly exceptional (17+).

[You could probably achieve interesting results with 2d20 for extraordinary checks: less than 1% for Strength 3, and about 38% for Strength 18. But this is YET ANOTHER system to try someday...). 

Other tables could be similarly replaced: 

- "Survive" checks (Constitution): roll under ability, you get a +4 bonus.

- Thieves' skills are extraordinary checks, but add level to your ability before rolling.

Of course, the exact numbers do not really matter. It depends on what you're trying to achieve.

This is just another example of ability checks I found interesting (I probably wrote more than a dozen in this blog already, this was probably the most recent, using 1d30).

Anyway, just another skill system for you to play with if you don't like sheets with lots of data or consulting tables during the game.