Space Invaders Extreme

This achievement needs a more accurate guide. It cannot be completed in 15 minutes - boosting this achievement takes 60-90 minutes if two players need all 25 wins.

The fastest way is to use a player match on Survival mode. Survival is slightly faster than Score Attack (since both players have to die in the latter). The game does not allow you to stick around in a lobby after the match, so most of your time will be spent re-inviting your boosting partner. Don't waste time changing the match settings each time, since nobody plays this anyway and you can't use them to speed things up.

Whoever is dying should get shot by the first bullet, then use the shields in the following waves to die a little faster. Shaves a few seconds off each attempt.

Not many people are online right now, so grab a friend to do it with.

invite them to the game and have them die quickly. (by moving into a rocket/missile)

and take it in turns dying. shouldnt take too long!
You can probly average around 3 a minute so,

around 15 minutes?