In interview for Gamasutra Spearhead Games share their answers to a question “How to develop a game quickly?”. These guys from Canada did this for 18 month and created their successful keys:

To accelerate work process helps understand that money finishes very fast and it will encourage each step to be thoroughly thought about.

Use one location couple times.
Create game location, create wisely with interesting storylines that make users interested in game location research couple times in order to find hints, paths etc. and pass a task or a level.

Simple and basic design.
Concentrate users attention on main characters of game, use bright and colorful foreground elements. Monotonous backgrounds are necessary only to help distinguish the appearance of rocks or buildings, don’t use any details, it saves artists resource.

Control movement of smart camera.
Let the users move the camera by 30-40%, it gives a feeling of cinematography. Think about spectacular angles, it is more profitable than a completely free camera. This lifehack allows to economise on level design.