A handfull of house rules. For BECMI/LL and Mutant Future.

[Agrippa]

BECMI/LL
1. Thief skills gain a +5% bonus per point of Dexterity bonus. I think that's a very common house rule here anyway.
2. Backstab, set spear vs. charge and lance attack scale with class level at a rate of +1 to damage multiplier per four levels after 1st.
3. While any character may attempt to backstab, set a spear against a charge or perform a lance attack, unless you actually possess the class ability needed, you only inflict 1.5 times normal base damage.
4. If a character attacks with a weapon that he or she is non-proficient with, that same character attacks as if at 1st level.
5. Multiclassing is allowed. However, to multiclass you must first reach 2nd or 3rd level in your current class. Then you must undergo a training period of one week per 500 experience (rounded up) to achieve 1st level in your new class. Afterword when you gain levels in this new class you use either it's THAC0, hit dice or saving throw progression, or your old class's, which ever one is better. Redundant class features use the higher progression of the two as well. You may advance in either class freely when you reach the 3rd level of your second class. In effect this is more like a combination of AD&D dual and multiclassing rules than anything else.
6. Hit dice for all classes except magic-user rise one step. Thief rises to d6 (for an extra 50 experience), cleric, halfling, mystic and elf to d8 and both fighter and dwarf to d10.
7. I also treat the three BECMI alignments differently than others. First the Lawful alignment places civil order, group effort and often times conformity above the the wants, needs and desires of the individual. It would correspond well with either one of AD&D's Lawful alignments. It's opposite Chaos proclaims the individual's right to take what he wants from others with little or no consequence. The AD&D alignments it would synch up with best are Chaotic Neutral, Chaotic Evil and Neutral Evil. And finally Neutrality, which aims to balance out the extremes of both. Whether this is through kindness mixed with individualism, simple benevolence or morally ambiguous heroism/extreme passivity. The Neutral alignment is best reflected in the True Neutral, Neutral Good and Chaotic Good alignments.

Mutant Future
1. I'm using Dyson Logos' Mutant Score rules.
2. PCs, significant NPCs and some monsters (read spidergoats) can take up to their constitution in negative hit points before dying. The redundant organs mutation multiplies this number by one plus its mutation modifier.
3. Levels rise at a rate of 1,500,000 exp. points after level 11.
4. PCs and prominent NPCs start with Con/2 in d6 or d8 hit points at first level and gain an addition Con/2 in hit dice at 11th level.

Combined A.K.A. Mutants and Mazes
1. Player classes advance as normal (1,250, ect. for thief for example) but total character level (the amount needed to roll for attacks per round, melee damage bonus and ability score increases) is the same as in core Mutant Future rules. This means that you can have a character with a higher class level then character level. It's pretty much a given this will happen.
2. Class level, not character level, determines saving throws and THAC0.
3. Saving throws vs energy attacks use the old vs spells values, saving throw vs death is the same, vs stun attack progression is equal to the old save vs paralysis and petrifaction save (I prefer petrifaction to turn to stone) and radiation saves are made with the old breath weapons value. These differ among classes as in LL/BECMI.
4. All LL/BECMI and Mutant Future house rules apply.

I have a few more specifically for Monsters and Mazes and I'd like to introduce an alternate energy or mana-like spellcasting system, with its own class. So, any ideas on what to add or subtract.

[Denim N Leather]

Nice job.

[Agrippa]

Nice job.

Thank you then.

[Agrippa]

So, now what else should I add if anything? By the way, I'm planing on both a brawler class for RC/LL and a Slayer race for Mutant Future/Mutants and Mazes.

[Agrippa]

I just added a negative hit points rule for Mutant Future.

[Agrippa]

Just added a seventh LL/BECMI house rule. I'm not sure how that one will go over though.

[Agrippa]

Fourteen house rules so far, how do they look?

[netherwerks]

These all look decent. Any thoughts as to starting funds or just leave it as-is? The Alignment re-jiggering might throw-off some monsters, maybe...

[Agrippa]

You're right about the rejiggering of alignment, that'll screw with some monster listings. But no, I haven't really thought about starting funds. It just doesn't seem important enough or interesting enough to change really.