Thunder Force IV

The game format is mostly unchanged from the previous game (horizontally oriented and forward scrolling). However, many of the stages now stretch beyond the height of a TV screen, which allow the player more space to maneuver and dodge incoming fire (but also makes it easier to miss power-ups). Also, the player now has the option choosing the play order of the first four stages, instead of just the starting stage like in Thunder Force III.

The weapon system is similar to Thunder Force III. Featuring the same upgradeable defaults, and unique extra weapons that are either exclusive, or were in previous games. Again, upon ship destruction, the weapon currently being used is lost, apart from the defaults. The CRAWs return, and basically have exactly the same function as their Thunder Force III counterparts. The speed setting also returns, although it is represented by a percent gauge from 25 (lowest speed) to 100 (highest speed).

The most significant addition to the ship arsenal is the Thunder Sword, a very powerful lightning-based frontal attack. At the game's halfway point, the ship receives an add-on part which enables the use of the Thunder Sword. From here, the one requirement of using the Thunder Sword is that the ship be equipped with CRAWs. When the ship is not firing any weapons, a charging noise is heard (followed by a chime when fully charged) and the CRAWs will appear to be surrounded with electricity. The next press of the fire button will discharge the Thunder Sword. The blast is stronger if charged longer and is at its strongest when fully charged.