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Paradox titles are on sale for the week at 50% off at GamersGate / GamersGate UK. Every day there will be a series that goes on sale for 75% off. The series today is Europa Universalis.
Europa Universalis 3 Complete = $3.74 / £2.49
Europa Universalis 3 = $2.49 / £3.48
Europa Universalis 2 = $2.50 / £2.50
Europa Universalis = $0.25 / £0.25
Europa Universalis Collection = $20 / £15
Bunch of DLC is also available.