If you dodge the meson cannon from the light blue ychoms, the defense is a smooth affair until the Dargslan comes. Barracks can also be stolen from them.
Garthogs do not surrender, but they do at around 88% of ychom injuries. If you listen and stop firing in time, you will have a barracks. In the original IG1, I don’t think viral infection at level 2 depends on the difficulty. If you are the first to report to the Colonel, you will get the radar that sees the carrier and you can kill it, so it won’t be 2. It’s good to wait for the 2nd infection, because that way you’ll have more time to produce if you extend the level.
Another thing I noticed in the original game: at the end of level 2, it is enough to blow up Destroyer 2 to the winning battle. In Open IG1 you have to defeat all the enemies, so it’s a little harder because you can’t take down the destroyer with total fire, taking care of your cruiser. However, in both games, the battle is a smooth affair if you place 5 ion guns on the planet Achilles and attack near the planet. The 5 cannons quickly take down the enemy. You can also attack with a single fighter.
On a difficult level, the Ychoms also have a space base on Center 3, orbit. It’s not on a normal level, but it’s harder to knock down a meson cannon because you have to shoot it too.