in the game are now split into two formats: the free-directional scrolling, overhead stage format from the previous game, and horizontal forward-scrolling stages which would become the series mainstay, dropping the former entirely. Each stage begins in the top-view perspective, where the player has to locate the cores of a certain number of major enemy bases and destroy them. After this is accomplished, the stage continues from the side-view perspective, which plays like a traditional horizontal scrolling shooter. After the boss of the side-view sub stage is defeated, the player moves on to the next stage. Building upon its predecessor, Thunder Force II introduced a weapon system that would become the staple for the rest of the series. The player's ship now has default arsenal of weapons which include a twin, forward firing shot, a single forward, and single backward firing shot, and a bomb shot in the top-view stages. By collecting certain items, the default weapons can be upgraded to more a powerful level. Also, the player could obtain a certain number of new weapons with various unique abilities by collecting the weapon's corresponding item. Once obtained, the weapons can be switched between at the player's desire, but if the ship is destroyed, all weapons are lost except for the defaults. The top-view and the side-view stages have different sets of weapons; losing weapons in the top-view stages do not affect the weapons equipped in the side-view stages and vice versa. Thunder Force II also introduced the CRAW add-ons; small pods which revolve around the ship. The function of the CRAWs is to block weak incoming bullets, and to provide extra firepower by firing single, normal shots. The player may acquire up to two CRAWs at a time, but will lose them upon ship destruction. Exclusive to this game is an item which temporally increases their orbit speed, making them more likely to block bullets.
Plot
Taking place soon after Thunder Force, the ORN Empire creates a powerful new battleship, the Plealos. Using this battleship, ORN once again attacks the Galaxy Federation. The outcome of the attacks result in the destruction of the Galaxy Federation affiliated planet of Reda, and heavy destruction on the planet Nepura, which ORN eventually captures from the Galaxy Federation. Eventually, the Galaxy Federation learns that ORN houses Plealos deep below Nebula's surface when not in use and takes the opportunity to plan an operation to take it down. They send the next iteration of their Fire Leo series of fighter craft, the FIRE LEO-02 Exceliza, to destroy ORN bases on Nepura and eventually find and destroy Plealos. The player controls the Exceliza and travels through a variety of stages to accomplish this goal. The cover image for the Thunder Force II Sega/MD/G package by Illustrator Marc Ericksen describes the attack of the advanced FIRE LEO-02s on Nepura utilizing its forward and rear firing ordinance.
Reception
Japanese magazineFamitsu gave the Mega Drive version of the game a score of 28 out of 40. UK magazine Mean Machines gave also reviewed the Mega Drive version, and gave it a score of 82%.