One of the best thing of GameJam is that, unlike the full games, most games in Jam are created aiming at only one or two main points, just like dishes made with fewer kinds of ingredients. It made easier to pick out each ingredient, taste it, think about how the cook made it, and why it tastes so.
Of course, the skill of “cooking & combining ingredients” plays a large part in the final result. But as a cook, it is very beneficial to know the taste and characteristic of every ingredient before cooking.
Here are something I found in these entries:

Violence is an instinct-level desire within people. Blood, brutality, screaming, broken limbs, etc. could stimulate such illusion of violence, raising the dopamine level.
Youkai uses the human enemies, it increases the feeling of violence too.
Youkai has equipped a dash-based killing system, player needs to rush through the enemies to take them down, and in the same time player needs to keep notice of other enemies around who are ready to attack. The pace of the game is relatively fast, and become faster with more and more enemies.
The game grants an invincible buff when players got 10-kills combo, the combo reward is good in itself, but IMHO, the buff is granted too frequently and breaks the FLOW state of player.

This is a well-made reflex game, hard, fast-paced, with strong beats, simple graphic is perfectly programmed to match with the music beat. Also have high requirement of precise control and unforgiving death.
All of this helps to bring player to focus on the game and enter FLOW state. Of course it could scare off many players too.
It reminds me of the “Super Hexagon”, but this one has more features and the difficulty is lower.

Well, we all know that instinct-level desire Freud paid a lot of attention to.
This game is quite straight to the point: keep the starfish away, the basic action is click and drag, when the starfish is red, the dragging will rip a piece of clothes.
Yeah, it fits the theme well. 

It looks like a plain idle game, its name suggests an idle game. But it’s not.
You will get no spoiler from me.
This game is not aiming at instinct-level or manipulative-level pleasure. Its main feature is humor and surprise. Such features are often one-time use and make them very low cost-effective.
But good humor and reflections-level stimulation might be more effective to make people to remember longer time.
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At last, a shameless self-promotion of my own game, hope you would have a play and give some opinions. 
