View source for Tips raceforthegalaxy

Base Game Only, 2 Player only variant.
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The game is won through Victory Points (VP). The 2 possible ways to get VP are: 
1. Playing developments & worlds. 
2. Consuming goods to gain the additional VP chips.

So strategy tips will be based one or both of these ways of gaining VP.

Broadly speaking, most common strategies go though 3 different phases.
1. Start of the game:
Money (cards in hand) is more important than VP at this stage.
Gain cards in hand by trading goods, normally from cheap windfall worlds, or exploring.
You may also see some small trading improvement cards which aid this strategy like 'export duties' or 'spice world'

2. Middle game: 
Develop a card drawing and/or goods producing engine by playing card cost saving and gaining cards. 
Examples will be 'Drop Ships', 'Replicant Robots', 'Diverse Economy', 'Consumer Markets'.
Not to be overlooked are lots of cards which aid free stuff in the produce phase.

3. End game: 
The game ends after a player reaches 12 developments & worlds or 24 VP chips have been gained. These two ways of ending the game also broadly categorize the strategies for winning the game.
You either aim to out develop/settle your opponent with superior card drawing/discount engine, or aim to build a produce and consumeX2 engine that nets roughly 6 more VP chips per turn than your opponent. Expansion will struggle to keep up with 6 points per turn, but each strategy can diversify into the other to take advantage of the opponent's phases (see Drafting / Leeching).
Recognize the turn the game will likely end, and build 6? point developments that gain lots of points in the final count. Build other high scoring worlds like alien worlds and military worlds.
Whatever you decide it should be to maximize your potential of hand and cards on the table, and looking to see how your position best plays against your opponents to secure victory.
Occasionally you may tell that the only way to victory could be to +5/0 explore to dig for that one final 6 point dev card that will earn you 14 points. Better to go down fighting than to simply concede.

Drafting / Leeching / Playing the opponent: 
Whatever you want to call it, the strategy of your opponent should be considered at all times. This is not just a multiplayer solitaire game.
So at the 'choose actions' initial part of the round, consider what benefits you the most, but also consider what benefits your opponent the least.
For example, if your opponent has very few cards in hand, their develop and settle options may be limited - especially if they have no develop/settle engine powers or military.
Alternatively, if their tableau has no produce powers, you might safely produce without gifting your opponent free goods and VP. It's even better if you have developments/worlds with production powers in hand, which guarantees that if they settle a production development/world, you get to develop/settle one too and remain ahead.

Stay flexible. Take and keep cheap, easy to play filler cards to leech develops and settles.
Occasionally you get the 'zugzwang' feeling, where both players would normally choose produce or settle (or any other action type) but neither do because insufficient advantage would be gained from calling it. An example of this would be two players with equal produce/consume engines - neither wishes to call produce when they could use another phase to try to outflank the opponent, so both players pivot to expansion until one player finds advantage in producing again.

So the likelihood and the beauty of the game is that there is no one strategy to beat all others. You must be willing to be flexible at all times to maximize your position's dominance over your opponent's.

Some small extra tips:
Yes, some games may only last 6 or 7 rounds and you've just been beaten by a very rapid cheap blue or brown consumex2 and produce tactic.
Leaving 0 or few cards in the hand after a round can leave you exposed. If you do this then you need to have a plan, like a alien yellow windfall world ready to be traded or something.
It's a race; always question your position and the end of the game, try to finish on a high, 6 point development cards are often played in the final round to steal the win.
A non military strategy can still deploy a 7 point rebel world with the help of the 'Contact Specialist'.
Don't blame the card draw, 95% of the time a credible alternative is available. It sucks to lose, play better next time!