I like the aliens of C.J.Cherryl, Larry Niven, James White, Frank Herbert and David Brin.
IMTU no Aslan, Varg etc. but there are Kzin, Knnn, Jockta, Gowachians and Jophur to name a few.
IMHO aliens with truly alien ways of thought are not for players to play. Playable aliens might have different physical and mental abilities, societies and cultural values; but they still come at problems the same way and understand logic (even if their value judegments are different).
I think the "rubber-suit" part is a bit unfair. Just because these aliens think in ways we can understand, if not agree with, doesn't make them a rubber-suit. The same simplification could be applied to human cultures, are they all just "rubber-suits" of one another. Dismissing something with the comment: "Yeah you dress it up different but it is all the same in the end?" is always true if you make the "same" part simple enough.
But cultural differences between aliens are where the role playing is IMHO. Heck what is polite and works best in Japanese business interactions is not the same as in the U.S.; yet we can certainly get along and work together. Nevertheless, the consumate cross-cultural liason will take into account those differences and behave accordingly to maximize the interaction.
Now for truely alien ways of thought I cut and paste part of what was one of my first posts here I believe.
All part of an effort to make aliens just not rubber suits adn run them with some consistency.
Here it is. Some of the non-human ways of thinking I have a hard time describing being a human. It's my first shot at trying to capture alien thinking.
This idea struck me about 5-8 years ago when I was reading both C.J. Cherryl's Chanur novels, White's Sector General novels and investigating the Myers-Briggs personality profile scheme. Cherryl had the matrix brain Knnn (I beleive without pulling down the book) and White had the relevant physiological aspects of alien life forms classifed with letter codes, Myer-Briggs looks at human personality with four binary concepts, the introvert/extrovet, sensing/intuitve, etc. concepts.
My cognitive classification:
Cognition is described by 4 areas: (1) Sense of Identity; (2)Thought Process; (3) Event Relational Process; (4) Temporal Perception. The non-human ways will appear non-sensical and illogical to humans (that's why they are alien) but strangely these alien cultures can still build starships, etc.
Generally, species which are the same in all 4 areas of cognition will be able to at least communicate effectively. Although cultural differences can lead to misunderstandings (see Sol's history), their brains basically work the same.
Aliens which differ in 1 area can be communicated with but with great difficulty even if the two species share a common goal and a desire to work together.
Species with two or more code differences find it near impossible to communicate or work with each other. The other species' actions appear chaotic, insane and are completely unpredicatbale to the other. In this situation, an intepreter species is needed to bridge the gap. I give some examples below after the classifications.
Alien Cognition Classifications
Sense of Identity - individual (I), collective (H), cooperative (C), emergent (E)
Thought Process - linear (L), matrix (M)
Event Relational Process -sequential (S), reflexive (R)
Temporal Perception -uniform (U), variable (V)
EXAMPLES:
Identity
I=humans, H=collective: many individual thougths form one group will/mind, there are no individuals (e.g., borg STNG); C=cooperative: individual minds can access a group mind but individuals still retain individual will/mind; E=emergent:individauls have no sapience but in groups a form of sapience emerges, also refered to as a hive-mind.
Thought Process
L=linear: individual concepts can stand alone, binary logic possible, concept of independent variables possible; M=matrix: no concept stands alone, do not readily grasp binary logic or concept of independent variables, grasp problems composed of multiply dependent variables readily.
Event Relational Process
S=sequential: effect follows cause, effects are the maifestation of cause, predictive theories favored; R=reflexive: cause is the manifestation of effects, theories often appear ad hoc or by fiat to S (sequential thinkers) but such species appear to more readily grasp faster than light travel concepts.
Temporal Perception
U=uniform: time percieved as proceeding in a linear fashion at a relatively constant rate; V=varaible: one of the hardest concepts for U (uniform) species to grasp, V species have a hard time grasping beginnings and ends as these concepts are understood by U species.
For example, Humans are ILSU as are almost all species in sci-fi, the Borg HLSU, the Knnn IMSU, a "hive" species might be EMSU.
Accordingly, humans may find it near impossible to understand the "hive" but can communicate with the Knnn, albiet with difficulty. The Knnn have a hard time with humans and the "hive" but can communicate with both. The Knnn can thus serve as go betweens or interpreters for the Human and "hive" species.
All PC species should be ILSU in my opinion, this is not a system primarily for PC development but for universe development.
For example, this cognitive system can be used to "explain" why aliens act in unexplainable and to humans irrational ways. The GM need not even need to explain, how can a ILSU do so. One role-playing aspect is through using an NPC interpretive species and being aware that aliens are not just beings with more or less limbs who breathe different air. Thus, some NPC species may become a valuable interpreter/diplomatic species even if they have nothing else going for them.
Just some thoughts. Constructive comments welcome.