Welcome to Moon Invaders! This game was created for the Ludum Dare warm-up contest #8.5. We were given a choice of either 24 contiguous hours, or 12 hours divided as we wish, to create a game from scratch. There were two themes which we could choose from or combine: "Anti-Text" and "Moon". As you can see, I chose to use both - the game contains absolutely no text, not even numbers, and of course takes place on the moon. I ended up spending less than 12 hours working, but since then I have enhanced the game quite a bit. All told, it has definitely been less than 24 hours work total, but I think it holds up very well, and I enjoy it a lot. You will too. You will.
Conceptually, this is a Tower Defense game, which are games I really enjoy, but I wanted to do something really unique. The "moon" theme got me thinking, and it came to me - Space Invaders! So, prepare to defend against Space Invaders by placing Towers. If you're wondering what was accomplished during the contest time, the Acid Truck and Power Station were added afterwards, as was the entire Research system, and of course this lovely graphical document (previously there was an all-text readme, which made for quite a learning curve). Aside from that, it was tweaks and minor bug fixes after the time.
Left Click with the mouse to do things. Right click to exit things (specifically Placement Mode and Upgrade Mode). ESC pauses the game, and shows you your current score. Q ends your current game, giving you a score. S toggles the sound on or off. Space makes the game run double speed as long as it is held.
The blue bars up the left side are your current money. Each mark is one Moonbuck (M$). The green stick men up the right side are your moonpeople. Don't let the invaders wipe them out! Each time an invader gets down to the ground, you will lose one moonperson. Lose them all and your game is over. When that happens, it will show you a screen with invaders on it. Count the invaders to see what level you got to. Click anywhere to move on from the Game Over screen.
At the bottom left of the screen are green icons which represent the different Buildings you may purchase. Their prices are displayed next to them. Click on a Building icon to enter Placement Mode. In Placement Mode, a transparent building is shown where your cursor is. Click to buy this building, or right click to exit Placement Mode. The building is shown in red if it can't fit where you are trying to place it. If you run out of money, you automatically exit Placement Mode.
At the bottom right of the screen are yellow icons (they will be red initially) representing the different Research processes you can purchase. They each cost one full bar of Moonbucks (M$160) - the entire screen tall! They are red when you can't afford them. Each one provides a valuable boost permanently.
At the top of the screen are evil Invaders. They are the reason you need to place buildings. Blow them up before they can land!
Once you have Buildings placed, you may click on them to enter Upgrade Mode. In this mode, you are provided with a list of Upgrades you can purchase for the selected Building on the bottom left. The bottom right displays a list of which Upgrades the Building already has. A Building can hold 10 Upgrades. Upgrades cost M$1 at first, increasing by M$1 each time you buy another for the same Building. This price is displayed next the Upgrades. Different Building types offer different Upgrade options. In addition to Upgrades, you can always Sell a Building by clicking on the Wrench icon in the Upgrade Mode. This gives you back 50% of what you have spent on that Building. Right click to exit Upgrade Mode.
This is the basic weapon of the Moon Armada. It fires constantly, straight up. A key strategy early on is to place one of these at the left and right ends of the battlefield to help whittle down the invaders so they take longer to descend.
You will definitely need some of these if you want to fuel your army. Each wave of Invaders slain grants you a bonus from Moon Central Command, but this bonus is not enough early on. Build Mines to keep ahead of the Invaders.
The big guns! This will fire a powerful homing shot which detonates to do damage over an area. The only downside is that it homes in on all the Invaders simultaneously, leading it to ignore the sides and just smash the middle of the group.
An incredible advance in laser technology, the Cryolaser, rather than being a source of heat, actually sucks heat from the air (on the moon?), freezing the Invaders it hits. Frozen Invaders move at half speed, delaying their inevitable arrival on the surface. The other nice feature of the Cryolaser is its piercing attack - it hits all Invaders in a line. The Tank only fires if it can see a target in its range.
The mighty Acid Truck spews a glob of acid at enemies, as the name implies. The acid splashes over a radius, affecting multiple Invaders. Acidified Invaders turn green. While coated with acid, Invaders take double damage from any weapon. Note that the Acid Truck has a high base damage, but the damage can't be upgraded, so you are better off focusing on the benefits the acid provides rather than the raw damage. Also, the damage is only dealt to the Invader directly hit - other Invaders in the splash zone only get the acid effect.
Though the Power Station doesn't attack Invaders itself, it pulses energy into nearby Buildings, boosting their damage for a short time. Affected buildings turn yellow. Tip: On the off-chance that a Mooninite Mine is energized at the moment it finishes digging, it will yield M$2 instead of M$1!
Enhances the effect of acid, so that it also inflicts damage over time, melting the Invaders to radioactive goo.
Mooninite coating for all your shells, increasing their penetration. This adds 33% damage to all weapons.
Enhances the crystallization effect of the Cryolaser, causing enemies hit by it to shoot out Cryospikes sideways. These spikes only inflict 1 damage (which cannot be increased), but they freeze the enemies hit. Strangely, the Cryospikes pass right through enemies that are already frozen, guaranteeing a maximum freeze.
Upgrades all Blaster Turrets with additional barrels, so they fire extra shots (with 1/4 damage) at an angle in addition to their main shot.
Makes missile explosions suck affected Invaders inward, clumping them together for your convenience. As an added bonus, it also increases missile explosion radius by 50%.
This extremely lethal upgrade causes all your Power Stations to emit an electrical discharge every time they activate. This shock is enough to instantly destroy any Invader caught in it.
Blaster Turret, Missile Commander, Cryolaser Tank, Power Station
Adds damage to the affected Building. For Power Stations, this increases the boost they grant to other Buildings. For the Missile Commander it actually gives +2 damage instead of +1.
Blaster Turret, Missile Commander, Cryolaser Tank, Power Station, Acid Truck
1/5s for Blaster Turret and Acid Truck, 1/3s for others
An important upgrade for almost every Building. Makes them fire faster!
A significant boost to the digging speed of a Mooninite Mine! Highly recommended.
Missile Commander, Acid Truck
This increases the blast radius of the affected Building, by an amount that I can't really quantify in numbers that would make sense.
Cryolaser Tank, Power Station
Another one that you just have to see for yourself. Increases the targeting range of the affected Building. This range is displayed when you select the Building. Power Stations affect all Buildings in their range. Cryolaser Tanks may target anyone in their range.
Increases the freezing effect of the Cryolaser.
Power Station, Acid Truck
Increases the lasting effects of both acid and energy charges (because I didn't want to make two different icons, okay?).
This Upgrade is unique, because it is destroyed with use. If you have any Bunkers when an Invader lands, a Bunker is destroyed instead of a Moonperson. This is a good thing, so you may want to consider keeping some Mines around later in the game! Note that when a Bunker is destroyed, it doesn't lower the Upgrade cost for that Mine. The maximum Upgrade cost is still M$10, however.
This isn't an upgrade, but it's in the Upgrade Menu for every Building. Click on it to sell the Building, recovering 50% of the Moonbucks you put into it.