Ok here are my solutions to the three main problems I've run into: Strength vs. Size, Hit Points, and Human Scale. I've also included some minor errata.
The Strength vs. Size Discrepancy:
A Mechamorph recieves a +4 bonus on Strength checks per size category above Medium and a -4 penaly per size category below Medium. This bonus does not include a bonus to hit or to damage. This rule will be applied in reverse to D&D/d20 monsters used as alien menaces.
Diminutive: -12 bonus on Strength checks.
Tiny: -8 bonus on Strength checks.
Small: -4 bonus on Strength checks.
Large: +4 bonus on Strength checks.
Huge: +8 bonus on Strength checks.
Gargantuan: +12 bonus on Strength checks.
Colossal: +16 bonus on Strength checks.
Immense: +20 bonus on Strength checks.
The Hit Points Discrepancy:
A Mechamorph recieves 10 bonus hit points per size category above Medium. This may seem like an unfair benefit, but with their relatively low AC's, the larger Mechamorphs will be getting hit a lot more often.
Large: +10 bonus hp.
Huge: +20 bonus hp.
Gargantuan: +30 bonus hp.
Colossal: +40 bonus hp.
Immense: +50 bonus hp.
Mechamorph Weapon Damage:
The damage listed for the Mechamorph weapons assumes a Medium size wielder. Use the Increased Damage by Size table on pg. 44 to increase the weapon damage according to the Mechamorph's primary form size. Again, this may seem unfairly weighed towards the larger Mechamorphs, but the lower AC and the size penalty to hit helps balance out the increased damage.
Human Scale:
With the changes above, (hopefully) one could play a human using the d20 Modern rules without requiring special rules. Since Mechamporphs have a +6 level adjustment, a human in a 1st-level Mechamorph game begins play at 7th level. Alternately, the player of a human character could run two characters with total levels adding up to 7.
Minor Errata:
Stealth: The Stealth skill is described, but none of the Mechamorph classes have it as a class skill. Stealth is a class skill for Scouts.
Speed in Alt Form: According to some errata I found at the FFG forums (
http://www.fantasyflightgames.com/cgi-bin/yabb/YaBB.cgi?num=1107136335), the speed of a Mechamorph in primary form is:
Medium: 40 ft.
Large: 40 ft.
Huge: 50 ft.
Gargantuan: 50 ft.
Colossal: 60 ft.
Immense: 60 ft.
Also, a bot's highest class level provides a modifier to speed, as shown below:
Controller: -10 ft.
Scientist: +0 ft.
Soldier: +10 ft.
Scout: +20 ft.
Other House Rules:
Carrying Capacity: Incorporating the Strength bonus rules from above, use the following formula to determine the carrying capacity of a Mechamorph: Strength + (2x Strength Check Bonus) = Effective Strength.
Size for Semis: The semi truck size is Huge, not Gargantuan, and includes such vehicles as busses, and large RVs. The alt form of a semi truck is only Gargantuan if it incorporates the trailer itself into the primary form. (Even big city busses aren't more than 30 feet long, which puts them well under the minimum size for Gargantuan. A semi truck with a trailer is about 50 ft. long, which is within the Gargantuan category.)
Use of d20 Modern: Feats from the d20 Modern and d20 Future books will be allowed for Mechamorphs on a case-by-case basis after review by the GM (me).
Use of Miniatures: I like using a battle mat and miniatures. In the absence of properly-scaled Transformers toys, I'll be using dice or other markers to represent characters. If you want, you can purchase a "Hot Wheels" car of the proper design to represent your vehicle alt form on the battle mat. They are just about the right scale for 10-foot squares.
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