This can be an extremely effective tower, like the Laser Tower, so it's best to put it beside your Storage Silos, Town Hall, Resource Harvesters, or anything lootable.
If you place two lines of blocks parallel to each other and have a Railgun at the end, the monsters will go between them in a line, allowing the Railgun to take them out easily.
This tower can work very well in a SDT, as it can shoot down the booby-trapped areas.
Like the Laser and Cannon towers, this tower is best used with the pathing of blocks, more specifically in a straight line (the Laser Hall of Death: two blocks in a straight line with the Railgun at the back, example below). It fires more damage than Laser Tower, and shoots an infinite line of fire, but has a longer delay before it can shoot again. Don't forget, the Railgun may decreases damage to a lot of shots. It will stop decreasing damage if the damage is now from 600.
Railgun has the longest delay between shots for all of the defensive towers (second is the Tesla Tower and third the Sniper Tower). You need to have monsters go in a straight line to have the maximum total damage, but fortunately, monsters will move straight to the entrances of your wall, and become a straight line by themselves. It damages all of the monsters along the infinite line of fire, but has difficulty shooting monsters in spread out packs.
*The railgun does not attack flying monsters (Teratorn, Fomor and Zafreeti), so it would be wise to protect it with a Sniper Tower, Tesla Tower, or Aerial Defense Tower.
- The railgun deals 4x the damage shown on its stats: 100dps implies that the railgun fires a beam of 400 damage and reloads to fire again every 4 seconds.
- So, a Level 6 Railgun that deals 500 damage (500 x 4 = 2,000 Damage per shot) could kill hundreds of Level 6 Octo-ooze (1,800 health) with a single shot, if they were moving in a straight line - as shown in the picture (Note: the Railgun in the picture isn't level 6).
- The Railgun is one of the strongest towers in the current metagame, the other being the Aerial Defense Tower.
- The Railgun has the longest reload time, making it vulnerable to attacks.
- It is wise to make a short maze so that the monsters will clump together, making the Railgun easier to land its beam. That way you won't waste the Railgun's potential.