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Polarity Defense
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About the game
Polarity Defense, called MAG(net) on its own title screen, is a top-down tower defense about magnets. In the middle of each map stands a crystal, the "embryonic core", and one or more portals send waves of little robots to take it. Portals are coloured red or blue, and so is the magnetism of the things in the game: your shots, your turrets and the robots that come out of a portal all carry a polarity, and the robots are surrounded by a magnetic field that pulls or pushes shots that carry one. The help screen of the game puts the rule in one line: build turrets opposite the polarity of the portals.
You play a small figure who runs around the map, shoots with a gun and builds turrets and walls with points. Points come from orbs that the robots leave behind when they are destroyed. Each map starts in build mode, where you place your defences before anything moves, and the waves begin when you press the space bar. There are six turrets (basic, fast, spread, beam, polarizer and reflector), each with a different cost, range and fire rate; the polarizer and the reflector do not shoot, they act on shots that pass through them (the polarizer gives a shot its own polarity and the reflector bounces it back). You can invert the polarity of the tool or turret you are about to build, and the beam turret goes after enemies of the opposite polarity first, weak ones before strong ones.
Seven maps are included, from "The Start" to a bunker with a big trundler at the end, and one of them, "Futility", starts you with no points at all. The robots come in several kinds, from tiny scrappers to slow, tough trundlers. The game can be played in English or Japanese (the Japanese translation is marked as work in progress by its authors).
It is a jam game, made in a short time, and it shows in a good way: it is small, it has some jokes in its text and a clear idea at its core. The music is by liqMix and the art and sounds by kettek, with menu art by Amaruuk.
Playing it here
Click Play, wait for the download (the game is about 9 MB and loads once) and click inside the game so it gets the mouse and the keyboard. From the main menu choose Solo Game, pick one of the maps and press Start Game. The network game of the original is not part of this version, so it is a one-player game here. Press H or F1 for the help screen. Nothing is saved: each map starts fresh.
Controls
| Input | Action |
|---|---|
| W A S D | move |
| Shift | sprint |
| Left mouse | shoot or construct |
| Right mouse | move or deconstruct |
| Middle mouse or Tab | invert the polarity of the tool or turret |
| Mouse wheel or 1 to 9 | select a tool or turret |
| Alt | show turret range |
| Space | start the waves, and confirm |
| R | restart the level |
| F | full screen |
| H or F1 | help screen |
| Esc | menu |
A few things worth knowing
Opposite the portal. The goal text of the game says it: build turrets opposite the portals' polarities. Red and blue are the two polarities, and a turret you place can be flipped with Tab or the middle mouse button before you build it.
Points come from orbs. Destroyed robots drop orbs worth points, bigger robots drop bigger orbs, and every turret costs points (a basic one 10, a spread one 20, a fast one 25, a beam 50). Staying close to the action pays.
Use the tools. Besides the turrets there are a wall, to block and redirect, and a destroy tool, to take a construction down again.
Press R to try again. A lost map can be restarted at once, and a different map can be chosen from the menu.
Frequently asked questions
Can I play with a friend? The original has a networked co-op mode. It was removed here, because the site never connects to anything besides itself, so this version is for one player.
Does it save my progress? No. Every map starts from scratch.
Does it work on a phone? It needs a mouse and a keyboard, so a computer is the way to play it.
Credits and licence
Polarity Defense (MAG(net)) was made by kettek (programming, art, sounds, maps), liqMix (programming, music, maps) and Amaruuk (menu art), together ketMix, for the first Ebitengine game jam, and is released under the GNU General Public License, version 3. The fonts are OpenSansPX (Apache-2.0), LanaPixel by eishiya (CC BY 4.0, also under the SIL Open Font License) and x12y16pxMaruMonica by hicc. For this site the game was compiled to WebAssembly with a few changes: the network game was removed, so were the web links of the credits and the logo of the game jam, and the music was re-encoded at a lower bit rate to shorten the download. The licence texts, the source of this build and the patch are linked from this page.