...And I decided to suggest some games which are:
1 - Playable and Fun.
2 - Prototypes, but with a VERY interesting concept.
Here is the list below:
Legent of Ball
https://itch.io/jam/gbjam-5/rate/90291
Top-View Zelda like game, but using only ball. Sound very simplistic, but it is a very fun little game. Only the ending was meh, but overall great game.
MARS TYPE I
https://itch.io/jam/gbjam-5/rate/90395
A nice little Shmup game, which even have 3 Boss battles. The one Boss is unfair at some point, but other than that, great.
Derelict
https://itch.io/jam/gbjam-5/rate/90454
I really enjoyable unique gameplay concept: You start on each section of the spacestation with zero gravity and you are trying to restore it to continue. Great idea. However at some point you meet some spike which they suck your life like in a second. Give it a go.
You're In Space And Everyone Wants You Dead
https://adamgryu.itch.io/youre-in-space
Devil Daggers IN SPACE!!! However this is only a Prototype for the competition and it is still awesome! Plus you can to mini planets which is always cool.
Descend
https://pastellian.itch.io/descend-prototype
Sadly you casn only play this battle with the skeleton and without music making it a little disappointed...However the idea is so great! It is Undertale with the fight merchanics of SNATCHERS. Hope for the to the developers to make it awesome.
CollectoNomicon
https://techforthat.itch.io/collectonomicons
Posting the concept art, because it is more enjoyable than the game sadly...The whole idea of a cultist go arounf collecting freaking elderiths horrors like Pokemons, it freaking radical! Hope for the best again to the developers.
Obviously you can try a play more awesome entries which I didn't had time yet to play. Here is the Whole list
https://itch.io/jam/gbjam-5
1 - Playable and Fun.
2 - Prototypes, but with a VERY interesting concept.
Here is the list below:

Legent of Ball
https://itch.io/jam/gbjam-5/rate/90291
Top-View Zelda like game, but using only ball. Sound very simplistic, but it is a very fun little game. Only the ending was meh, but overall great game.

MARS TYPE I
https://itch.io/jam/gbjam-5/rate/90395
A nice little Shmup game, which even have 3 Boss battles. The one Boss is unfair at some point, but other than that, great.

Derelict
https://itch.io/jam/gbjam-5/rate/90454
I really enjoyable unique gameplay concept: You start on each section of the spacestation with zero gravity and you are trying to restore it to continue. Great idea. However at some point you meet some spike which they suck your life like in a second. Give it a go.

You're In Space And Everyone Wants You Dead
https://adamgryu.itch.io/youre-in-space
Devil Daggers IN SPACE!!! However this is only a Prototype for the competition and it is still awesome! Plus you can to mini planets which is always cool.

Descend
https://pastellian.itch.io/descend-prototype
Sadly you casn only play this battle with the skeleton and without music making it a little disappointed...However the idea is so great! It is Undertale with the fight merchanics of SNATCHERS. Hope for the to the developers to make it awesome.

CollectoNomicon
https://techforthat.itch.io/collectonomicons
Posting the concept art, because it is more enjoyable than the game sadly...The whole idea of a cultist go arounf collecting freaking elderiths horrors like Pokemons, it freaking radical! Hope for the best again to the developers.
Obviously you can try a play more awesome entries which I didn't had time yet to play. Here is the Whole list
https://itch.io/jam/gbjam-5