Just to elaborate on this, the idea is that metal extractors take a while to 'charge up' and killing an enemy mex will reset its charge. With this game mode on raiding enemy mex's would become much more beneficial.- Added 'Progressive Mining' game mode (default off), all mines start at 25% efficiency and raise to 125% over a few minutes, death resets this.
Not sure how it'll actually play so if anyone tries it or has any comments / suggestions please post here.