Age, Agency, Amorphism, Approach, Ascent, Assemblage; Beginning, Bisection (or Trisection, or ...); Causation, Change, Circumstance, Conformity, Continuity, Convergence, Conversion; Dimensions, Direction, Distance, Distortion, Duality (or Triality, or ...), Duplication (or Triplication, or ...);
Effect, Equality, Existence, Expansion; Form; Identity, Increase, Infinity, Interaction; Life, Light, Location; Mixture, Motion, Multitude; Opening, Order, Oscillation; Period, Power, Production, Progression; Quantity; Relation, Repetition, Revolution; Size, Substitution, Superiority, Stability, Symmetry, Synchronism; Time, Transferrence, Travel; Union; Velocity, Violence.
59 themes, with the final list being whittled down to 1. Voting continues until the day before the competition, so there's no opportunity to prime yourself - and that's just the first stage of voting. Second and final round is over the 24 hours before the compo starts. That's a heck of a lot of false positives. I sorted them in alphabetical order for easier perusal and reference.
No game is built around just one theme; other thematic influences are always present to help flesh out the gameplay and lend some complexity to things. Virtually all racing games today, for example, incorporate some form of economy, such that advancement is no longer solely a function of your adeptness at the actual races, but also of your savvy in the purchase of additional vehicles that increase your race ability as well as open new race opportunities to you. Many racing games have dual forms of currency, a "respect" system that proceeds from your race performance (including sub-objectives like completing the race without a scratch or parallel objectives like completing all races placed third or higher) as well as a literal cash system based on the associated race purse. This layering of objectives and considerations can lend a game nuance when skillfully brought together, but it can also make the game seem random and haphazard if not intelligently integrated.
The PyWeek competition themes are suggestive of artistic, aesthetic or political commentary/criticism on life - on humanity, I should say, given that "Life" is one of the themes. Age, production, repetition, time, violence, equality, existence, conformity, change: considered collectively, these are recurrent motifs in our history, and perhaps that's the most logical design basis of all.
Not just history in the sense of a dry reading of events that occured in the distant past, but history as a chart, a graph of aggregate opinions, behavior; history as a tool for projecting the future. A histogra[m|ph]? How does a game introduce the notion of history? My first-stab answer is consequence. My second is causality (Causation is one of the themes, too). If you do this, that will happen - consequence. If that happens, then you will no longer be able to do the other, or you will have to do the other, or you will have to contend with the other while attempting to do the fourth. On the flip side, this is here because that happened. That happened because the other was done by so-and-so. And so forth.
How this is actually expressed in the game can take many forms, from the inherently historical process of turn-based play, to an explicit system of instituted deprivation (penalties) and availability (bonuses, power-ups) as a by-product of user decisions.
More on this later. I need to go get some work done on a few other things.