An upgrade system is the backbones of any simple, addictive game.
Done right, an upgrade system will convince your players to stay in your game world, playing until they have unlocked every upgrade imaginable.
Progressively Earn Upgrades
Once an upgrade has been unlocked, it’s appeal drops significantly.
It is no longer an unreachable goal in the player’s mind, but is within their actual possession. They will use it, learn how it works, and soon grow tired of it.
That’s why it is crucial that you continually offer new upgrades for the player to unlock.
After every level the player should have the ability to purchase new upgrades. But don’t force the player to purchase any. The next levels should be completable without them, albeit a bit more difficult. This allows the player to make a decision: Buy an upgrade right now, or save up for that super cool/powerful upgrade in a few levels.
By stretching out the number of upgrades a player can earn at one time, you can keep players in your game, playing level after level. Think of your favorite tower defense games. The reason they hook so many people is because they progressively allow you to unlock more powerful towers. The appeal of new and more powerful types of towers is what keeps gamers playing. Take that appeal away, and tower defense games grow boring.
Take Bubble Tanks Tower Defense 1.5 for example. I had a blast playing and using the new features that came with unlocking more powerful towers.
Then, I discovered Sandbox mode.
BOOM! I was done with the game. Able to use all the towers and see their features, the game lost it’s appeal to me and I quit.
You can limit the upgrades a player is able to earn at once by:
- Making powerful upgrades more expensive
- Requiring a previous upgrade before the player can unlock a new one (see Upgrade Trees)
- Revealing new upgrades as the game progresses
Mystery and the imagination play a key part in the creation of a compelling upgrade system.
The best upgrade systems keep a player guessing as to the exact details of the upgrade they are about to purchase. Of course, you don’t want to mislead the player about the nature of your upgrade, but you do want to develop some mystery around it.
Things to make the player’s imagination wander could include:
- What it looks like in use. For example: the swishing motion of a sword, the bullets (or lack of bullets) in a gun, the color of a jet stream from a rocket, the opening of a parachute as it slows your character, etc.
- What sounds it makes. Is there a cool roaring sound of jet engines? A swish of a slashing sword? The less than flattering thunk of a stick?
Provide a New Experience
Upgrade systems work because with each upgrade a player unlocks, the upgrade modifies the way the gamer plays the game. It gives the player more control over the way the game plays out, and makes the game more fun to play.
Upgrades that modify the player’s control over the game are great, but what about upgrades that add new features to a game?
Now you’re getting somewhere. New features can completely change the way a game is played. This new experience can keep a player intrigued and immersed in your game world.
Features that make a player’s life easier fit perfectly into the cycle of compelling upgrade systems.
Upgrades such as auto-firing in a turret defense game, a jetpack in a platformer and a vehicle in a run-and-gun game will not only give the player a new experience but will help the player unlock more upgrades; keeping them in your upgrade system.
These three points should have your players coming back to your upgrade system again and again, until every upgrade has been unlocked.