The Challenge: Plant a flag on this planet, Proxima Centauri!
Its the nearest real possibly habitable planet located near Alpha Centauri, 4 lightyears which is made accesable by RSS Constellations
The main constraint would be that FTL drives are not allowed, but you are allowed to use the slower than light (STL) engine from KSPI Extended
like KSPI-E Daedalus engine and/or magnetic nozzle.
Here is an example :
The alternative, travel by photon sail