The Tennis game mode is the first secret that can be unlocked.

In the courtyard outside the factory, there are two trucks next to the big button on the ground.

The left truck has a box of bombs, take them and go to the first hall of the factory.
On the upper right side, there is a darker wall. Blow it up to reveal the secret opening leading to the Tennis map.

There are 6 silver grenades hidden all throughout the levels of the game. Finding a grenade teleports the player back to a panel at the entrance showing the progress in the quest of finding all grenades. Once all silver grenades have been found, a teleporter activates, leading to the hidden map Kitchen.





Here are the levels in which all silver grenades are located:

- Train - on the side of a wagon


- Waterfall - tree to the far right corner when having the waterfall behind your back



- Raceway - on top of a truck, jump from the bridge


- Lighthouse - behind the lighthouse


- MOON - open end of the central yard


- SnowyMountain - small bended tree next to the crate for tiny people

There are in total 104 golden grenades in the game, however the game only displayed 102 as my total. The final boss grenade is never awarded nor counted in the total.

The achievement only requires 90 golden grenades, so it is possible to get the achievement without finding any secrets.

- 90 golden grenades in the normal levels of the game
- 1 golden grenade for the first boss

- 3 golden grenades in the level Tennis
- 5 golden grenades in the level Kitchen

- 5 golden grenades in the main hub without entering any levels
When entering the factory for the first time

Outside the factory, left of the entrance

Outside the factory, inside a truck right of the entrance

In a crate in front of the MOON level

Behind a row of crates in a corridor leading to the SnowyMountain level