Sunrider: Mask of Arcadius

As Captain Kayto Shields, embark on a galactic voyage of heroism and survival. With his home world destroyed and his nation conquered, the inexperienced Captain Shields, and his newly minted vessel, the Sunrider, are left as the only hope against a galactic evil intent on subjugating all......

—from the Steam page blurb

Sunrider: Mask of Arcadius is Visual Novel/Turn-Based Strategy game that is mix of spaceship and mecha warfare and wacky harem comedy with an underlying serious drama as the core.

It's available on Steam for free, though it's High School AU spinoff Sunrider Academy isn't. It has a sequel called Sunrider: Liberation Day currently in development, as well as a prequel tie-in novel called Sunrider: Venizcar and novelizations of the first two arcs of the series (covered in Sunrider: Mask of Arcadius )

Tropes used in Sunrider: Mask of Arcadius include:

A Mech by Any Other Name: The mecha are called Ryders.
Bowdlerise: The Steam release was censored, but this can be quickly undone with a patch that mostly uncensors one really mild h-game scene.
Cool Mask: Discussed. Kayto speculates with his crew over why Arcadius wears a mask, with theories ranging from it granting immortality, to allowing another "Arcadius" to be a Legacy Character, and so on. Turns out all proposed theories are somewhat true.
Crapsack World: Ongessia. So much so it was EVEN WORSE than the crime and disease ridden hellhole it currently is before the Solar Alliance tried to improve things. Unfortunately, they also aren't doing much to help by continuing to mine the planet, which only increases the pollution and poverty, which also increases the crime.
Doomed Hometown: On the level of an entire homeworld. Cera is quickly conquered in the prolouge of the game, and Kayto has to watch his hometown get blown off the map in the process.
Easier Than Easy: Visual Novel mode, which makes the battles nigh impossible to lose.
The Empire: PACT. Ironic, given they were founded to oppose the empire that preceded them, though some of their leaders are somewhat aware of this and are trying to remedy that, or at the very least have moral reservations about what they've become.
The Federation: The Solar Alliance is fairly morally upright one for the most part, though it has issues with bureaucratic inertia and morally grey behind the scenes stuff.
Fighting For a Homeland: The crew of the Sunrider who hail from any world conquered by PACT.
Freeware Game: Though updates are available must faster to backers of the creator's Kickstarter.
Frickin' Laser Beams: Roboteching lasers are in vogue with most of the units in the game, good and bad alike.
Kinetic Weapons Are Just Better: Due to proliferation of shield technology, kinetic weapons like railguns are much more effective since they ignore the shields, though lasers do much more accurate damage when they can get past the shielding. Missiles are de facto kinetic weapons, though can be easily shot down or intercepted. All assault weapons like handheld pistols/machine guns count as kinetics, but are much, much weaker.
Heroic Sacrifice: Sola attempted this in her backstory. The player can choose for Ava to do this to take down the Legion.
I Am Legion: What the main flagship of the PACT fleet is named after. Also meaningful, as Arcadius himself can clone himself and admits he's one of many, many clones.
Infant Immortality: Averted with graphic majesty in part two of the game.
Katanas Are Just Better: Icari's Phoenix and the PACT/Ryuvian Nightmares are equipped with gigantic katanas, with the former even sporting a wakizashi just to add on some samurai portrayal accuracy.
La Résistance: Kayto Shields is the only senior member of his nation's military thrust into this role by default by virtue of his planet's conquering the subjugation of it's military.
Mood Whiplash: The harem comedy hijinks often happen right before or after the serious and quite dark parts of the game.
Mooks: PACT and the pirate forces wield similar grunt units.
- Elite Mooks: PACT Elites. Nightmares later count as Degraded Boss versions.
Nintendo Hard: The game in it's later parts, especially on the harder difficulties.
Non-Lethal KO: Ryders can retreat when they hit zero HP, unless battle conditions dictate a game over if they die.
Not Distracted by the Sexy: Ava maintains her professional demeanor in front of Kayto even when he's naked. Likewise, Kayto proves fairly immune to Claude's attempts to seduce him despite her purposeful fanservice attempts.
Older Than She Looks: The art style for some of the girls tends to make them look like young teens instead of young adults. On a more serious note, Cosette barely looks older than the same, but there is a reason: her age was frozen in time thanks to a genetic degeneracy caused by radioactive pollution.
One-Hit Polykill: The Vanguard Cannon of the Sunrider can kill everything in it's area of effect. The Legion has the same ability.
Operation: Blank: Operation "Wedding Crash".
People's Republic of Tyranny: PACT is allegedly benevolently socialist/communist, but the red military theme and aggressive gunboat diplomacy make this claim ring very hollow.
Player Mooks: You can hire out Alliance Cruisers and Mining Union frigates to augment your forces.
Point Defenseless: Missiles when not obstructed by flak. Rockets are basically this trope minus the weaknesses of missiles.
Real Robot Genre: The Ryders are more military based despite being rather Humongous Mecha in size.
Roboteching: Most laser weapons arc for no apparent reason when fired. Averted with missiles, which work like real world cruise missiles.
Shut UP, Hannibal: Sola, does this to Prototype Arcadius when he goes into a rant about being immortal. With her Ryder's sniper rifle.
Space Opera: Although it's rather dark despite some attempts at levity.
Space Pirates: Cosette runs one, and there are others you have to hunt down in side missions.
Sole Survivor: The Sunrider is the only vessel of the Cera fleet to escape the prologue unscathed. Chigara is the only survivor of the Diode Catastrophe. Icari lost all of her family to PACT troopers, and Sola is the only survivor of the long ago Ryuvian Civil War.