LÖVE

Hi guys,
I am a bit hesitant about adding unlocks to my game and I would be interested to know what you think about it.

Here is the context :
I am making a 3D maze game for android. It will be a paid game with no ads. In this maze game, you have access to the map but you don't know your position on it. So you have to find your position first, then follow the map to reach the exit before the end of a timer.
The game has 6 difficulties/modes :
* zen mode : you have unlimited time and can show your position on the map
* easy : you have a compass and the mazes are smaller
* medium : you also have a compass and the mazes are bigger
* hard : no compass
* insane : no compass and very big mazes
* secret (I don't want to spoil, but it's really difficult)

There are 4 themes (textures to give different looks to the mazes)

What I did is put the secret mode as a reward for completing level 5 in "insane" difficulty.

I'm wondering if it could be interesting to make the "zen mode" and some themes rewards too. It could bring some sense of progression for the player. But at the same time, it feels a bit artificial.

What do you think ? Did you put some unlocks on your previous games ? What was the players reception about these ?

I made my decision

But can I have some opinions on the subject ? Do you tend to add unlocks to your games ? Do you know how people perceive them ?

I don't have any feedback as a dev, but as a player I generally enjoy unlocks if they add to the gameplay by adding new modes/levels/options/etc - especially if it challenges me to try something different or unusual that I may not have considered on my own. Looks like this would fit the bill for me!