Write down your design pillars.
This is the foundation of your game and should never change.
Your whole design should tie back to these pillars.

All Features Supports Teamplay

Teamplay is king and cannot be exchanged.
In doubt, the feature with higher teamplay-value will be chosen.

Valuable Intel Needs to Be Deserved

Complex puzzle and high reaction games rewarded the player with helpful intel which are valued by players.

Failing is a Process

Experience and skill through try out is acceptable.
It is okay to show the player ui nudges, but there is no finger pointing or kindergarten caretaker mechanics.

Unique and Multipurpose

Most things can be used in different unique ways, also the gadgets or weapons.
E.g. you can shoot on some interactive points and they will react to it in special ways.

Adding Content is Easy

If there are two solutions, but one makes it easier to add more content to the game, this should be taken. Regardless it is heavier to implement.