Lostech

Lostech refers to technology developed during the Star League era that was lost in the brutal Succession Wars that followed the Star League's collapse. From 2570 to 2780, the Star League developed advanced technologies, ranging from 'Mech design to terraforming entire worlds, representing the zenith of human technological development. Following its collapse, the Great Houses fought for control of the Inner Sphere in four massively destructive interstellar Succession Wars lasting two and half centuries. Lostech represents the lost vestiges of a greater age that would not be seen again until 3028 when a Star League era bunker containing a still functional memory core was discovered on the planet Helm.

It is 3049. Two decades have passed since the discovery of the Helm Memory Core and the preserved Star League era technological data was shared with universities and militaries across the Inner Sphere. Since the events on Helm, a technological renaissance has spread to all the Great Houses. How this will be manifested in MWO is uncertain.
 * So far, the development team have remained very true to canon so it is expected that some reclaimed Star League technology will be present.

Lostech Weapons
Technologies known to have existed, but lost in the decline of the Succession Wars:

Recovered
Practically all Pulse Lasers were amongst the rediscovered technologies from Helm:

Lostech Electronics
Technologies known to have existed, but lost in the decline of the Succession Wars:

Recovered
On Helm rediscovered technologies:

Rumors
Formerly stated to be Lostech:
 * ECM
 * XL Engine
 * Endo Steel