Aliens in the Plot
Probably in the plot there is already at least one alien race. But do you remeber that in Elite half of the planets were inhabited by alien races? Of course it was a very rudimental system with no influence on gameplay, but with some work its potential towards commerce and relationships could be greatly enhanced. I already developed some possible characteristics which could affect the gameplay, and i'm sure that with some work and research we could be able to find out more.
EXAMPLES:
1) Intelligent races evolved from carnivorous are basically oriented towards aggressiveness and individualism. Omnivorous species are less aggressive and probably have an ambivalent behaviour towards individualism (just look at the human race); herbivorous species should be pacifist and gregarius.
2) Hydrogen-breathing races should have difficult relations with oxygen breathing ones, due to their very different constitution, so only a limited range of communications should be permitted. Anyway technology in an hydrogen atmosphere is quite different from the one in an oxygen atmosphere.
3) Some species could be biologically compatable with some others (so that you can trade food, luxuries and medicines between them), and some others don't.
4) The physical appearance could also condition a race's needs; an anphibius race could need some type of equipment thought to work underwater while a race of giant animals (probably born from a planet which receive a strong radiation from its sun, cause the high energy levels connected with it) will require a large amount of food and giant machinery.
5) Simbiotic and group-intelligence race should need a wider range of goods (for simbiotic races), or they could need high amounts of the same good (for group-intelligence races).
6) Some ancient civilizations could be telepatic, so avoiding the linguistic problems.
7) Added to the physical and evolutionary characteristics, there could be also cultural differences (militaristic, pacifistic, expansionist, philosophic and so on).
8) Of course nobody forbids that some of the planets you are exploring could be the native planet of a new alien race; and nobody forbids that that race might be able to build spaceships. You might even meet spaceships of some unknown race (and their behaviour will depend on their evolution as well). Of course in meeting a new race you have to solve the linguistic and cultural problems.
But, what i'm suggesting to do is not a lot of alien race just wearing the hats: "militaristic", "cunny", "logical", or something similar (note that in the examples I showed how the characteristics of an alien race should condition far more than the relations with other races); I'm suggesting to do a serious work, based on evolution theories and native world's characteristics, to create an algorithm capable to obtain consistent and realistic alien races, at worst even randomly (the terms "consistent" and "realistic" are referred to actual evolution theories, of course).
The same thing for biology; as stated in point 3), I specified that some species could be enough compatable to exchange food and medicines, while others are not; of course, to be totally consistent the thing should work in a slight different way: some species could be enough compatable to exchange *some* food and *some* medicines while others are not (if two species developed on very similar worlds there should be some chances that some of their basic components are the same).
The same thing for technologies: some of them could be compatable, some of them could be partially compatable (requiring you to have some spare parts to adapt their tech to yours), and some of them should be totally incompatable. Probably the characteristics of homeworlds should influence how much the technologies are compatable (IE: an oxygen based tech is useless for aliens breathing hydrogen)
The same thing for communications: there could be races with different degrees of knowledge (or comprehension) of human languages, so different degrees of communications might be developed; you could also meet alien races which does not know your language (suppose you are exploring an unknown part of the galaxy), so that you have to develop a common language on your own; that could be possible or not, and it could require variable time depending on their affinity with you; probably the presence of a xenologist in the crew (or between the passengers) would help a lot. Some ancient civilization could even be able to communicate telepathically; anyway i think this is a too destabilizing feature and I suggest it is used for no more than one alien race strictly related to the plot.
Xenology: The algorithm should develop the most high number of characteristics to influence each aspect of your interaction with aliens (from the trading to the communications, passing through their behaviour); but it's not automatic that the player knows all this details when he meets a new alien race; so for each race xenology studies should be carried on (not by the player, of course... :-)), and only well studied species will show all their characteristics.
Crew: why not having the chance to hire an alien in your crew? He will have his own advantages and disadvantages. (though they are principally related to the food/and or water; so if you don't like their use, forget this paragraph; but if you are starting to like the idea of consistent aliens in your crew, it might be a good idea to reevaluate the supplies concept as well). Of course you should be able to provide all his needs, and to communicate well with them. (or *they* should be able to communicate well with you; of course you can't hire an alien in your crew if you are not able to speak with him without misundertanding anything more complex than "what time is it?")
To summarize: I'm suggesting to work on a difficult algorithm to create a variety of consistent alien races. Of course i'm volunteering to work on it, but alone it's impossible to obtain some consistent result (that's a work which requires more than one mind); moreover before working on it I would like to know if people here lieks the idea or not (doing work without reason is not my idea of spending some pleasant time :-))
Note: Probably we'll have to do an hard work for the algorithm, but once we have developed it, the work for coding should be not so hard; i think that the most difficult part is to figure out all the possible charactetristics and understand how they could interact between them and the extternal universe; once we did so, it should be relatively simpler to implement it, or to apply the modifiers due to the alien races to the prices or to their reactions, or to the technology or else.