Here we go again: another recycled GOG weekend sale that focuses exclusively on Topware titles at a nifty 60% discount. Notably, Earth 2140, Earth 2150 and Earth 2160 will set you back approximately £1.39 ($2.39) a pop, including all their expansion packs and several post-release AI improvements. They're both excellent RTS games and a steal at this price. Septerra Core is also down to a similar level, providing a meaty and exciting JRPG experience, and undercutting GamersGate in the process.
Chances are you've already leapt at this sale during one of its earlier appearances, but if you've somehow managed to emerge from the Steam Summer Sale without a heaving backlog, you might want to check it out.