Based on ShoppaTraining_v2 by TheMadCharles (from this thread), I have made a Shoppa Training mission.

It's very simple: Each turn a target and a weapon crate spawn. There is no goal, but you can try to destroy the crate as fast as possible and become better for Shoppa. Play as long as you wish.

That's basically it. The rest is “just” gimmicks.

Here you can download the Shoppa Training:
https://bitbucket.org/Wuzzy2/hedgewars-wuzzy4/raw/18ecb569c6ac3fbbeb7f2be60e6dbadfb1b60d93/share/hedgewars/Data/Missions/Training/ShoppaTraining.lua

Rightclick the above link and save the file into Data/Missions/Training.

I have put much effort into making this thing useful for you to keep track of your Shoppa skills.
First of all, your time is displayed for each collected crate and for each destroyed target.
The training keeps track of skill levels which you can try to increase over time (all of this is optional and just for fun):

• Speed: Destroy x targets in row in under y seconds per turn
• Endurance: Destroy x targets in row
• Safety: Destroy x targets without taking damage in between

Speed level 1 should be possible for beginners with 4 targets in under 75 seconds each. The hardest part in Speed level 1 is not the time, but to not screw up.
Average Shoppa players should at least reach Speed level 5: 8 targets in 30 seconds each.
The highest Speed level is level 9 with 12 targets and 15 seconds each.

The other skill levels are mainly there to motivate you to not screw up your turns, even if you are too slow to advance to the next Speed level.

There are also a few hidden additional achievements for some sick Shoppa skills.
Note that skill levels and achievements are not saved when you leave.
Note this is a mission which never ends, you can only quit with Esc.

Also, remember you can always review the mission text and a list of your skills and achievements by pressing Esc or the pause key (like with any other mission).

I am also trying to get this mission into Hedgewars officially.