I decided on running OSE for the foreseeable future, but I'm removing the thief class from my game and redistributing its capabilities to the other characters. I'm not here to discuss why I'm doing it, but how, so let's get to it:

Things everyone gets:

• Backstab: Kind of stupid that's not the case already, though I might diminish the bonus on attacks to +2 and/or make the attack do max damage instead of doubling it.
• Open locks and Find or remove treasure traps: I'm rolling these up together in a new Meddle with Mechanisms skill with a 10% chance across the board. It requires thieves' tool (even for traps), and the restrictions on retries for each type of mechanism still applies as per the original rules.
• Pick pockets: Scales with DEX with the table below. Yes, I know, another thing for DEXtrous characters to be good at. Whatever. Has the same caveats for targets above 5th level as the original rules.
• Read Languages: Since this is a higher level feature, I turned it into a Identify language skill that serves to identify what a language you don't speak is. Was made for written text but I guess could be used for spoken language as well. Doesn't grant you the ability to understand it. Scales with INT as below.

Other skills:

• Move silently: Halflings can move silently with 20% chance of success.
• Climb sheer surfaces: Dwarves are acostumed to climbing and can climb any stone, rock or earth surface using only their hands. A roll is required for each 100' to be climbed. The chance of success is 5-in-6, but it drops to 4-in-6 if wearing heavy armour or carrying a heavy load. If using encumbrance rules, you could drop this penalty and instead make the distance between each roll depend on their movement rate.

That's it. I thought of letting Elves move silently in forests as well, but decided against it as they are already feature rich at first level.