Crackpot inventors, evil geniuses, heroic monster hunters with a technological edge: all of these fall under the purview of Mad Science. Being a Mad Scientist requires the advantage Arcane Background: Mad Science (an Unusual Background costing 5 points).
Gadgets created by Mad Science all, obviously, have some level of the Gadget limitation; they also tend to be breakable. ALL Gadgets (those created by PCs at any rate) have a Malfunction Rating of (at best) 16+; for attack powers an attack roll of 16+ indicates a malfunction (annoying on 16, debilitating on 17, and destructive on 18); for non-attacks, a roll is made each time the gadget is used, with the same annoying/debilitating/destructive result. A malfunction rating of 16 is a -5% limitation; lower malfunction ratings are allowed and even encouraged, with rolls below 16 also causing 'annoying' malfunctions.
Costs FP is generally inappropriate for gadgets, though individual gadgets (or a set of linked gadgets) may have Costs FP with an Energy Reserve. Takes Extra Time is a common limitation for large, complex machines that need to warm up.
Each individual power after the first bought with Mad Science inflicts insanity - the inspiration provided by the Manitous has a price. There is no hard rule for this; insanity can range from the quirk-level (dislikes, etc) to full-blown 15 or 20-point mental flaws; this is worked out with the GM while the power is constructed. This applies a Source: Mad Science limitation on the power, worth -1% per point of the associated flaw.
Annoying malfunctions limit the use of the power or ability for a period of time, usually at least the remainder of the scene. This can be represented by -2 to attacks, half value of DR, or something else that leaves the power functional but less useful. Repairing an annoying malfunction generally requires an hour or two in the lab and no skill roll, though some simple gadgets such as bulletproof vests may simply be readjusted.
Debilitating malfunctions completely prevent the use of the power or ability until repairs can be made, though they generally don't put the character in any direct danger (though the critical failure may, if it is an attack power). Repairing a debilitating malfunction generally requires six hours in the lab, and an appropriate skill roll (Repair or appropriate Armory at -4; Weird Science at no penalty).
Devastating malfunctions cause significant damage to the gadget and potentially to the user and/or his friends (in addition to the normal effects of a critical failure, for an attack). Repairing a devastating malfunction requires 16 hours of lab time (2 days, or one frenzied all-day session) and an appropriate skill roll (Repair or appropriate Armory at -8; Weird Science at -2).
Talents and Applicable Skills
The Mad Science talent (10/level) adds 1 to all Repair, Armory, or Weird Science rolls to repair gadgets and to rolls to activate or control powers; it does NOT add to attack rolls involving gadget weapons. Reaction bonuses apply to other Mad Scientists.
Any decent Mad Scientist will have the Weird Science skill (IQ/VH), which is NOT entirely the same skill featured in the Basic Set. Weird Science is used to figure out an unfamiliar gadget created by someone else, to repair gadgets, and in some cases as the skill to use a gadget's powers. Many Mad Scientists will also have Engineering, Physics, various Mathematics skills, Machinist, and other 'creative' science skills. Some will also have mundane Armoury for repairing and constructing non-gadget weapons and armour.