This is insane. The AI is playing perfect and has a 3:1 advantage. Not only 3x more Worms, also 3x more heavy weapons. My team doesn't look so good after three dynamites were used on it. I have no idea how to get this one done. I had the CPU down to two and even one worm in overtime, but guess who won by shooting over half the map and hitting through a 4 pixel wide gap...

Any strategy hints?

Uh.. I'm not yet there, but try to use enemy worms as a cover, or hide your worms if you can't find any. They always look for clear worms if a target is near their friends. If they hit their teammate, it's time to split. Hide your worm and watch them shoot each other :p

Practise makes perfect.

Those CPU worms have had over a decade of practise, after all ;)

I actually just finished Challenge 20 yesterday.

Save your heavy weapons for groups of worms, also try to keep tabs on who will be going next.

Since you get to play every other turn each team has to wait 3 turns before getting to play, that can give you an advantage.

Also keep track of which teams have used their heavy weapons, knowing that can also save your skin.

It'll still be tough, and you'll probably end up with one worm versus a couple of theirs.

A couple other things that I think will help: don't worry too much about completely killing their worms at first, having them around and sticking close to a group of enemy worms can cause them to not fire at you, or do damage to their own worms.

It takes quite awhile for a cpu worm to get another turn (each other team will go, and when it does get a turn it will be cycling through the other worms in the team), giving your worms several extra turns before getting back around to the worm you just attacked (or attacked you) - use that knowledge against them.

So rather then finish them off, don't waste your fire power unless you don't have another option. Hitting a guy with 35 points with a grenade (45) effectively wastes 10 points of damage, instead, hit a strong worm that has closer to 100.

By the time you start actually killing the worms off they will all be weak, 1-hit kills.

Hope that helps!

I've just finished Challenge 20. I personally found 13 the hardest, and from there I started putting one worm "away" and high up each time, ready for sudden death.

Everyone goes down to 1 point of health at sudden death, making killing (and being killed) easy.

With this tactic, try concentrating on the enemy worms high up during normal time using your remaning 3 worms, with the other tucked away. Try and spread the remaining 3 out to cover each bunch of enemy worms, of course leaving the enemy nearer to the water and concentrating on the worms higher up. When the water starts rising, most should drown pretty quickly.

Keeping the air strike for this part of the game is also pretty handy, to take out whoever's left and possibly in a safer place (in terms of protection from rising water) than you...

The above is a good tactic!

Practise makes perfect.

Those CPU worms have had over a decade of practise, after all ;)
It's spelt 'practice'

Well hey...
www.wiktionary.org
Practice makes perfect...

And Plasma saves the day again by spelling 'practice' right.