Starship Hector is a deliberately old-fashioned shooter (even for its time) designed for core shooter fans and geared towards gathering high scores. To this end, it has a couple of alternative timed challenges to the main campaign mode that players can try to practice getting high scores.
The game was used in Hudson's Caravan competition, which traveled across Japan collecting high scores from competitors for a country-wide contest. Subsequent Caravan games would be released on PC Engine. Starship Hector would later appear in the Super Famicom's Caravan Shooting Collection with its two NES predecessors Star Force and Star Soldier. A GBA compilation, Hudson Best Collection Vol. 5: Shooting Collection, also features the same three games.
The vertical-scrolling stages are very familiar to Xevious fans, as the ship is able to shoot airborne targets with their guns and ground-based targets with their bombs, and never vice versa. Unlike Xevious, bombs continue flying vertically upwards like gun bullets, instead of stopping short at a pre-defined point (i.e. when they hit the ground). Like Xevious, there are also special hidden areas the bombs might hit which create a smart bomb like effect, removing all other ground-based targets in the vicinity. Chances there that there's one nearby if there's a particularly heavy presence of ground-based enemies. Additionally, the player can constantly bomb the odd rock devil heads on the ground for small health boosts, as the player's ship has a health bar rather than the customary single hit point.
The horizontal-scrolling stages are far more like Gradius or R-Type. Players can still bomb targets on the ground, but must be aware of the arc that bombs take to fall downwards. Once the bombs touch down, they continue rolling across the ground until they hit something much as they do in the vertical-scrolling stages.
In both modes, there are no power-ups for either of the player's ship's weapons. Occasionally, this will mean that avoiding enemies is safer than trying to destroy them, as many require multiple shots. At the end of each stage is a boss, which usually can only be destroyed by systematically blowing up each gun turret and segment that comprises it.