Unconscious guards in the Metal Gear series are differentiated from dead guards by a little halo of stars merrily orbiting above their heads. As the guard gets closer and closer to waking up, one star at a time will cheerfully ascend heavenward and vanish. A guard with five stars won't be waking up for a while, but a guard with one star could open his eyes any time... (Weirdly enough, the MGS games are usually considered serious. Of course, it does fulfill a gameplay function.)
In The Legend of Zelda: Ocarina of Time, when sneaking around the Gerudo Fortress, Link can stun Gerudo guards with either his Hookshot or arrows. If arrows are used, then the Gerudo falls down, and has stars circling her head.
The Legend of Zelda: Link's Awakening has lights orbiting Link's head whenever he's knocked down by That One Miniboss, Blaino, who soon uses the opportunity to uppercut Link back to the dungeon entrance.
In Final Fantasy IV an actual bird circles the character being attacked by Confusion spell animation followed by question marks at the end of the spell animation.
Technically, the ones in Gold/Silver are bird balloons.
In Pokémon Heartgold and Soulsilver, in the minigames, the birds are replaced by Psyduck.
In the Pokéwalker, the player's Pokémon experience this; when knocked out, in the journal, stars circle that Pokémon's head, Blissey for example. For large Pokémon, the stars that circle its head are not in the background, but above the background. Wild Pokémon do not experience this trope; when the HP hits zero, they run away.
Also in the Gen V games during the Poke Transfer minigame, circling stars appear if two Pokemon bump into each other by mistake.
Bubble Bobble (not in the NES [or Virtual Console] version): When Bub/Bob dies, after he spins out, he falls on his back and dizzily sees stars above his head while his eyes circle around (no spirals) before poofing away. It's also in the first Puzzle Bobble/Bust-A-Move game, in which the sprite animations are based on Bubble Bobble's.
Bubble Symphony: Bub and Bob still fall backwards upon death (even though they spin out differently; their original spinouts being taken by Coro and Kulu) and their eyes circle around but no stars are visible.
In Puzzle Bobble 4 / Bust-a-Move 4, when the player loses, Bub/Bob immediately gets dizzy, gains spiral eyes, twirls around, falls forward, and has birds circling above his head. Also the case for Bub in the Game Boy Color exclusiveBust-A-Move Millennium, and Bob in SPACE Puzzle Bobble. (Bob the unlockable character cries instead in BAMM.)
Bubble Bobble Plus (WiiWare): They spin out as fast as in the arcade original and end up lying on their back before they poof away. There are no hovering stars. According to this.
In Team Fortress 2, a player hit with a baseball will be temporarily stunned and treated to a third-person view of their character in a dazed trance, complete with "BONK!" written over their heads with stars circling it.
There's also the Halloween version (When they get in contact with the ghost in Harverst and one of the Headless Horseless Horsemann abilities), where instead of "BONK!" it's "YIKES!".
In the Wii Punch-Out!!, when an opponent is stunned, something related to their nationality/gimmick will circle their heads. For example, Piston Hondo has circling egg sushi.
Unsurprisingly, as it's basically a knockoff of the Punchout series, Glu's Super KO Fighter 2 uses the trope in the same fashion when a fighter is knocked down. The fighter 15 Cent, a parody of 50 Cent, sees circling dollar signs, for example. Your character sees simple stars. The trope actually factors into gameplay, as the fewer circling items above the character's head, the more likely he is to be able to get back up.
Happens in Monster Hunter to monsters if they get smacked in the head with a blunt weapon enough times, or if they get hit with a flash bomb. Can also happen to the hunters if they get hit with certain attacks, or receive too many hits within a short span of time (In which case the number of stars deonotes how much time is remaining in the stun).
Circling birdies denote being stunned in the Tales Series, which can happen to pretty much anyone who suffers enough abuse in a short period of time, or if they get smacked upside the head with a Pow Hammer.
Any enemy stunned by Commander Keen's Neural Stunner in Keen 4, 5, and 6 will see stars around its head — if you don't, that means the stunning is only temporary. Fortunately, this applies to Keen himself if he gets stunned by his own fire in 6.
The final frame of Mario/Jumpman's death animation in most versions of the original Donkey Kong includes a plain white halo. It was likely intended as this but limited by hardware.
In the first two Donkey Kong Country games, Diddy will get a ring of stars over his head if you lose a life while playing as him. In Donkey Kong Country Returns, enemies you stun with the peanut popgun/ground pound get an actual birdie circle.
Most of the Mario Party games feature this with birds if a character is stunned by something like dangerous areas or hazards on the game board.
In Super Smash Bros. Brawl, any character stunned by a broken shield or reflector, exploded Deku Nut, Mewtwo's Disable move, Weavile's False Swipe, Wario's Wario Waft, or Luigi's Negative Zone will be rendered immobile and a tweeting sound effect is heard. Button Mashing may get the player out of the "stunned" effect sooner.
In Super Smash Bros For 3DS and Wii U, stunned characters have circling stars.
In one cutscene of Sonic Unleashed, as Chip explains on how he lost his memory, when he said "And then nothing," he sees stars and tiny versions of himself circling his head (Wii version only, for they are replaced with normal stars in all other versions), as seen here.
Dr. Eggman did not get the same thing; in another cutscene, Eggman sees stars after a kid throws a rock at Eggman's head, as seen here.
Any time a character in Sonic the Fighters is knocked onto their back, they briefly see circling stars.
In Sonic 3 & Knuckles, Knuckles gets circling... something orangey-yellow when he starts coming to after being briefly knocked out during a cutscene in Hidden Palace Zone. Due to graphical limitations and the size of the circling objects, they're hard to identify, although they are most likely birds or abstract shapes.
Creature World also has Seeing Stars Head Bonk, and Seeing Birds Head Bonk, in which users see stars, or birds when they wear the hat. There is also a hat in which users have hearts in their eyes and hearts circling the user's head.
Bomberman games sometime feature this with birds or stars when players or enemies are stunned. In Bomberman Blast, if a player is stunned, the tweeting of birds can be heard from the Wii Remote Speaker.
MapleStory has this trope; players and enemies that are dazed get a halo of circling mushrooms. This happens after taking damage by a certain enemy and so on.
Toonstruck features circling stars at one point. And you need to take these as an item.
The Neverhood: While they're not shown, falling to the bottom of the drained lake for the first time will result in a cutscene of Klaymen being stunned, which is accompanied by typical "birdies" sounds.
In Epic Mickey Mickey sees Gremlins after getting slammed in the face while freeing one from a safe. The gremlin then flies over to him, takes a moment to glance between Mickey and the circling versions of himself, then comments on what a good likeness they are.
Power Instinct has this starting with the first game, but one of the stuns are flying hearts. The second game takes this to the next level with circling objects, such as people, sushi plates, chicks, and fish.
So you are playing Fighter's History, and you fight an opponent. However, if you hit a weak spot multiple times and when a character is stunned, this game has circling objects that differ from each character, similar to Darkstalkers. Take Liu Feilin for example. When Feilin is stunned, she sees circling fairies. For another example, Liu Yungmie sees circling unicorns when she is stunned.
Happens often in the Raving Rabbids series after they get hit on the head with an object.
In Crusader of Centy, the first boss, the Big Bad Wolf, attacks by hitting himself on the head with a hammer, causing stars and birds to circle his head. He then uses these objects to damage you.
In Sheep, Dog 'n' Wolf, Ralph gets stars circling over his head when running into a wall. And in one instance, Daffy Duck gets them too.
In World of Warcraft, a character can get "dazed" if a monster hits him from behind, resulting in a 50% reduction to his movement speed for 3-4 seconds. While he's dazed, an animation of swirling stars appears over his head.
In Spelunky, stars (or little birds in the remake) circling over a lying character indicate that they are simply stunned rather than killed.
Justin Bieber, Robert Pattinson, Nicki Minaj, Pitbull and the other various celebrities featured in the online boxing game "The Brawl" experience the stars version of this trope when they take enough abuse.
Quik the Thunder Rabbit has circling birdies when the player character suffers Collision Damage.
True to its desert theme, in Tiny and Big when Tiny gets hit by a boulder thrown by Big without dying (or is stunned for, ahem, other reasons), a set of small rocks circle around his head.
Wii Sports Resort has Cycling, a bike sport. One of the features of this sport is that it has a stamina system. If a Mii's stamina runs out, he/she stops in his/her tracks with stars circling his/her head.
Wii Sports Club has the Boxing sport from the original Wii Sports. One of the differences, though, is the inclusion of a stun system in which after a Mii's HP goes down to a certain point, he/she is stunned and sees stars, leaving him/her unable to punch, though he/she can still dodge.
In Little King's Story, you can cause a couple of bosses to get hurt in ways that induce Circling Birdies And Stars while they're stunned. If the Onii King is in the throes of a tantrum when an Onii has thrown something to him for him to throw, he won't catch it, and be stunned. If you cut a totem pole while the Owl Hag is standing on it, she'll fall and be stunned.
Iosa the Invincible from Iji has lights orbiting her head when stunned. She sees less and less as she gets close to recovering.
This occurs a couple times in Injustice: Gods Among Us, when an opponent is caught in Wonder Woman's lasso of truth or when Zatanna puts her opponent in a hypnosis stars will circle their heads.
In one version of Battle Chess, Rook takes Knight and Bishop takes Knight both involve head trauma for the knight, complete with "cuckoo" sound effect.
In the first Pikmin game, Olimar has circling stars after he crash lands.
In the second Pikmin Short Movie "Treasure in a Bottle," the Yellow Pikmin's plan is to use a Bomb Rock to free the Red Pikmin trapped in the bottle. It works at first, but the Red Pikmin falls back into the bottle. When the three Pikmin go to the bottle, the Red Pikmin that was stuck is now dazed and the Red Pikmin has circling stars around its head.
In Chip Chan Kick, stars will circle over stunned enemies while a twittering sound effect plays.
In a cutscene in Rita James and the Race to Shangri La a Yeti which gets clonked by a low-hanging stalactite sees light flashes and spirals.
Animal Crossing City Folk uses this trope when you go to the city and enter Katrina's Fortune Shop. No matter what you ask her, Katrina will drop an anvil or wash pail on your characters head and your character will hear tweeting birds and see stars for a few seconds.