I've just started playing Downwell after getting it for almost nothing during the Winter sale, and I didn't think I was going to enjoy it as much as I am. Quite the fun little arcadey thing. This also had me thinking about similar smaller games I own, so I started playing a bit of Super Puzzle Platformer again, which is also a very nice little game. I dabbled a bit with Super Hexagon as well, but I suck at it as much as I've always have. ;)

Anyway, I was wondering if you guys were able to recommend other bite-sized arcade games like these (preferably available on GOG). Thanks in advance.

Monolith
and the DLC.

Top down twin stick shooter. Roguelite with very satisfying shooting. Kinda like Isaac or Nuclear Throne.
Very nice aesthetic too, very polished.
Each successful run for me has been less than an hour. Maybe around 40 minutes?
Even with them short runs i've put in over 50 hours so far.
The DLC adds a lot of things too.
Also, they are both pretty cheap.

Highly recommended.

Crimzon Clover. The main game takes around 35 minutes for a successful clear (which is not going to happen on your first attempt, trust me), but there's a time attack mode where you have 3 minutes to score as many points as you can.

VVVVVV (by the same developer as Super Hexagon) has an unlockable secret lab, and in it is the Super Graviton, where the goal is to avoid random enemies while bouncing up and down. Normally you'd have to get all 20 trinkets to unlock it, but under the Accessibility Options there's an option to unlock it (as well as Time Trials of each level) without actually having to play through the game.

Ys Origin has an unlockable Arena mode that's quite fun (as well as a boss rush mode that lets you play just one boss at a time without having to go through the entire gauntley), but you unfortunately need to beat the game normally first with each of the three main characters, and the main game is semi-lengthy with some substantial unskipable cutscenes. (There's a fourth character, but he is only playable on boss rush and arena modes.)

I've not tried it yet but i've heard very good things about 198X:
https://www.gog.com/game/198x

Not on GOG, but maybe interesting nonetheless:

https://store.steampowered.com/app/286100/You_Have_to_Win_the_Game/ (this one is for free!)

https://store.steampowered.com/app/310700/Super_Win_the_Game/ (sequel to the first, €7,99)

https://store.steampowered.com/app/732430/Superflight/ (fly a wingsuit, try not to crash into rocks, €2,99)

These are three "bite-sized" games, that I had some fun with.

Vertical Drop Heroes HD?

Hello dtgreene,

I would not call it "bite-sized" in the sense of small bits and bytes, afterall, it is a significant larger game than Super Hexagon or other suggestions. But I definitely second the suggestion of VVVVVV!
It was my first 'indie' game and still is one of my favourite games todate.
And yes, the Super Gravitron mini game within it is more like Super Hexagon, albeit easier or a little bit more fair.

I am not sure, if it matches the criteria, but maybe Mr.Mumbles could try Jump king, as well.

Kind regards,
foxgog

Broforce:
https://www.gog.com/game/broforce

It's an over-the-top arcadey 2d sidescrolling shooter.

The game has several missions. Missions each have several levels (except for covert missions where you only have one level and one life). As long as you beat a level you can pick up where you left off later.

Each time you rescue a bro, you become him and the rescue counts as an extra life. If you are killed and still have lives, you'll return to the last checkpoint you triggered as a new bro.

If you lose all your lives, you either restart the mission or restart from a larger check point (usually before a boss).

I find it works well for short or long playthroughs.

Each "bro" is a parody of an action movie character and each has different abilities.

Examples::
Rambo -> Rambro
Commando -> Brommando
Blade -> Brade

edit:
The only caveat I have is that levels with bosses can be more challenging and take longer. Quitting during them may result in having to replay other sections.

I also recommend waiting until it goes on sale. While enjoyable, it is a short game.

Oh, and Ctrl+F12 toggles the hud. It's never mentioned anywhere, but I find it more enjoyable without it.

VVVVVV may not be bite-sized, but it has a sub-game that is. Ys Origin is the same way, only unlocking that sub-game is a lot of work, which is not the case with VVVVVV.

Interestingly enough, Celeste (not on GOG, but DRM-free on itch.io) has Celeste Classic as a bite-sized sub-game; only difference is that Celeste Classic is available on its own for free at (auto-playing sound warning):
https://mattmakesgames.itch.io/celesteclassic