Super Destronaut: Land Wars

You access this mode by selecting 'Arcade Modes' from the main menu then 'Classic Mode'. Classic mode is a standard wave-based mode.

You receive points for killing enemies, between 100 and 500 points, depending on the type of enemy. As you kill more enemies in succession, your multiplier bar, which is located beneath your score, fills up. Depending on how full it is, you receive more points for killing each enemy. The multiplier bar slowly decreases as you are not killing. Also, when you take damage, you lose some of your multiplier. The key to reaching 300,000 points quickly is keeping that multiplier bar as full as possible.

When you max out the multiplier bar, you enter 'Rampage' mode. For a short time, you are given a second weapon to deal double the damage. Take advantage of this as it only lasts about 10 seconds. Maxing out your multiplier during this time does not extend Rampage.

When you kill an enemy, you gain a small amount of health. It also drops money which can be used to buy more powerful weapons. Collecting money also increases your multiplier.

If your health is depleted before reaching the point threshold, you fail the game mode. The points are not cumulative over multiple playthroughs, so you need to do this in one go. But, if you've reached the point threshold, allow yourself to be killed and the achievement will unlock.