ETBlight adds two new player classes to ET, the Scientist and the Super Soldier.

I'm a Super Soldier. What do I do?

You use your adr...invisi-needles to become INVISIBLE and create havoc behind enemy lines. Or whatever you can think of.
By default (starting with  version 1.1.9), Invisible Super Soldiers can move at ludicrous speed and jump about 4 times higher and longer than the slowest double-jump you ever did on a jaymod-server.

Naturally, with great power comes great nerfing: Invisible Super Soldiers cannot attack, use any item, push players, take flags or carry objectives. Opening doors will instantly make you visible again.
Invisibility lasts max. 5 seconds and drains the chargebar 100% at all times.
When visible, the Super Soldier move slower than other Classes, regardless of equipped weapons.

You can alter Super Soldier behaviour with

It's possible to f. ex. completely disable invisibility and let the Super Soldier run at normal speed, then he can act as a sort of alternative to the Soldier. You should probably consider giving the poor now-meaningless dude some Tripmines with g_blightWeapons before he commit suicide, if you do this.

The world looks a little different when you're invisible.
Field of View changes and you get a cloudy drunken/underwater sensation:

super soldier invisibility

You will be completely invisible to other players, but other players can still hear you,  and they can still hit you.
It can be a lot of fun to "Guess-hit" an invisible player.

Other facts:
The Super Soldiers primary weapons consist of the Mini-Browning and the Q3X1, both of which are lousy long-range weapons - the Super Soldier is simply no good at long ranges.
Pistols are his most effective long-range weapon.

The Super Soldier can not go Prone.

The Super Soldier have a little more Hitpoints/HP than the Medic, to a maximum of 165 HP (moves slower, does not have access to normal SMGs).