A Tale of Two Kingdoms

An indie Adventure Game created by Crystal Shard. The player takes the role of Maeldun Whiteblade, who is framed for murdering King Vortigern of Theylinn. While on the run trying to clear his name, he has to deal with a goblin invasion, an assassin on the loose, an evil wizard trying to stop him, and the quirky faeries of Thierna na Oge.

The game is freeware and can be downloaded here.

Contains examples of the following tropes:

Action Girl - Branwyn.
Arbitrary Skepticism - The monk considers faeries a "figment of man's imagination" while an army of goblins is camped just a few miles away.
Awesome McCoolname - Maeldun Whiteblade.
Awesome Moment of Crowning - The good ending. And no, you're not the one getting crowned.
Baleful Polymorph - Taranis's modus operandi; you spend the entire sixth chapter in the shape of a rabbit.
Better Manhandle the Murder Weapon - The reason why you're accused of murder. No, you can't avoid it.
Brutal Honesty - Lady Branwyn and Geraint. Subverted with Cailte.
Captain Ersatz - The protagonist's sprite looks very much like Prince Alexander from King's Quest VI (see Spiritual Successor, below; funnily enough, in the original concept, Maeldun is a captain ersatz of Graham, not Alexander).
Celtic Mythology - Most of the names, characters and plot points are borrowed wholesale from Celtic myth.
Chekhov's Gun - Branwyn's dagger.
Clear My Name - The protagonist's goal in the game.
Dark Is Not Evil - Arawn Nos.
Deadpan Snarker - Branwyn always has something to add to the conversation between Maeldun and another character when she is present. Geraint is also not bad at this.
Everything's Better with Princesses - this is a Fairy Tale, after all.
Evil Sorcerer - The Big Bad.
Failure Is the Only Option - Want to catch that assassin? Sorry, you just can't.
Fairy Tale
Fantastic Foxes - the Pooka.
Genre Savvy - If you are a Celtic Mythology buff, you'll have an easier time solving the puzzles.
George Lucas Throwback - This is a 2007 game deliberately stylized, in terms of gameplay and graphics, to look like it had been made 15 years before that.
Have a Nice Death - as common in adventure games.
The High Queen - Nimwe, the Seelie Queen, is an elfin lady of incredible grace and beauty.
Historical Villain Upgrade - An in-universe example. The tailor believes that the king was assassinated by Muldan Blackblade, a barbarian with a massive black sword.
I Am Not Shazam - the second of the two kingdoms is the faerie realm of Thierna Na Oge, not the invading goblins. A few of the reviews got this wrong.
Info Dump - The opening narration.
Informed Ability - In the opening Info Dump, Maeldun is presented as a great warrior. In the game, he is anything but. Branwyn pointedly explains to the fawning Iseult that Maeldun is their diplomat, and Branwyn herself is the great warrior. She'll show it if you lead the barghest into your camp.
Interface Screw - one of the spells Taranis casts on you inverts the mouse controls.
Knight Templar - Geraint.
Lost Forever - There are a few items in chapters 1 and 2 that cannot be retrieved once you end those chapters. There's also several sidequest objectives that can only be done early in the game. Plus, a lot of the inventory objects that can be applied to multiple puzzles are one-use items.
Mistaken for Murderer
Moon Logic Puzzle - The game's creators definitely tried to avert this, but many instances do crop up, particularly the infamous murder mystery. Some people consider this a Guide Dang It, but the information is all in the game, and through elimination you can figure out that the assassin is really Cailte, in case you wondered.
Multiple Endings - Five, ranging from the sad to the evil to the good.
Names to Run Away From Really Fast - Rashakk Skullcrusher.
Not So Different - Lord Geraint and Lady Branwyn, when you think of it. Both command the armies of their master/companion, are completely loyal to them and would do anything they can to protect them. Both are brutally honest deadpan snarkers to some degree. Branwyn hates Vortigern and Geraint because the latter's armies destroyed here village. Geraint hates Maeldun and Branwyn because the latter's armies vanquished Vortigern's empire. Both cases are mentioned in a conversation between Maeldun and Rhiannon. (Perhaps as a Lampshade Hanging.)
Our Giants Are Bigger - Morholt the giant is a classic example: huge, dumb, mean, and cannibalistic. If you outwit him a test of strength, he softens up and becomes your pal.
Pardon My Klingon - Goblins use "gronk" as a catch-all swearword.
Proud Warrior Race Guy - The goblins, and especially Rashakk Skullcrusher.
Redemption Equals Death - Geraint, more or less. He doesn't die so much as get turned into a vulture.
Reconstruction - The game attempts to recreate the fun and joy of old VGA quests while jettisoning their annoying moments (Unwinnable, Guide Dang It, etc.).
Shout-Out: Dozens of them, especially to King's Quest games.
- There are at least two to Discworld. You can find "Twurp's Peerage" in the monastery's library, and Maeldun describes cider as a drink made of apples. "Well, mostly apples."
- Near the castle, you meet a talking scarecrow. You can give him a brain, and afterward he will name himself Baum.
- If you try to enter a stump, a message will appear, requiring you to insert disk 23, followed by 'Oops, wrong game.' Also, on the monk's bed there is a book called 'The Mystery of Ape Atoll,' (no, not THAT Ape Atoll) which involves swordfighting, dark magic and the undead.
Spiritual Successor - Of the King's Quest series. It was even originally conceived as a Fan Sequel to the aforementioned franchise.
The Dev Team Thinks of Everything - You need to buy a flute, and the most obvious ways for getting money are gambling with the goblins, using the wishing well, or selling the sorcerer's figurine. In the unlikely event that you miss the opportunity for all of those, it may seem like you're stuck... but you can still find a pot of gold under the rainbow; if you've already lost that, you can sell Morholt's crystal.
The Fair Folk
True Love's Kiss - required, of course, to wake the sleeping princess. And no, you're not her true love.
Unwinnable - One trait of old Sierra adventures that wasn't adopted by the game's creators.
World of Ham - Although there is no voice acting, the dialogue is bombastic, grandiose and full of Ye Olde Butcherede Englishe. Very often Lampshaded.
Ye Olde Butcherede Englishe - the fairies talk like this. Blossom the changeling also tries to, but isn't very good at it. It's also Subverted and Lampshaded many, many times, particularly in this Easter Egg:

Helloeth! Thou appeareth to be playingeth an adventure gameth. Wouldeth thou liketh help with thateth?

You Fight Like a Cow - as a Shout-Out, you can try this in your fight against Rashakk. It doesn't work.