eleazar wrote:OK, how can i write and effect to make a certain species' ships 25% more destructive in battle, or is that possible?
I don't think that's possible at the moment, for several reasons:
At present, I think I recently posted about how ship part stats are mostly gotten directly from the numbers written into the part definitions, and not through effects. A ship doesn't actually have a single damage meter, but rather has a stat for each weapon part that gets added up to determine its damage as reported and used in game. Consequently, there's no effect usable to modify that stat. This is different from ship meters (not part meters) like stealth or structure, which (I think) are modifiable with effects.
More generally, even if effects could usefully modify ship part meters, there's an issue with order of effects being applied... When deciding what effects get applied to what objects, currently the order is: species, specials, techs, buildings, ships (hull of a ship, then parts of the ship). That means all effects related to species in the universe get applied, then all effects related to specials, then techs, etc. For ships, it's the hull of ship 1, then the parts of ship 1, then the hull of ship 2, parts of ship 2, etc.
The consequence of this is that if effects were determining the actual stats of ship parts, there would still be no way to have a species give a 25% boost to those stats because the ship part effects come after the species effects, and thus at the time the species effect could be applied, all ship part meters would be 0.
The whole effects system of FreeOrion has a limitation or incompatibility with modifications of this type (+25%). This is notable because lots of people seem to want to default to using percentage based modifications, when really the FreeOrion effects work better for fixed modifications like +5, or modifications that vary based on things other than the meter being modified and that are persistent between turns. So, +2*population is OK, but +2*target_population is not, as the population is roughly persistent between turns, but target population is recalculated from 0 each turn by adding up all relevant effects. Similarly, +0.25*current_meter_value works differently depending on what other effects have already acted on a particular meter that turn.
That said, if / once part meter effects have been implemented, you could do something in the part itself to give certain species a bonus. For example, the part could have a base damage of 8, and then there could be an effectsgroup for the part to give +2 to the damage if the species of the ship is one of those in a list.