A mod to expand or compress the period of game time over which new units and infrastructure items will become available.
It adjusts the availabilty dates of everything by taking the number of years since 1850 and muliplying it by the factor you select – the default is 1.25.
For the mathematically inclined:
New Year Available = (Old Year Available – 1850) * scalar + 1850
You can change the scalar by manually editing the settings.lua file, but the mod is Common API compliant, so you can do it that way too.