Watch out for the airplanes flying from right to left. So I didn't have a very hard time with this, except for the making my code I wanted it to be easier working a couple days ago. I wanted to make the levels differing code at the end so it wasn't interfering with the code structure. But this proved to be a difficult task since it wasn't working on a real Odyssey 2. It wouldn't get past the title screen.
But eventually I made it work. I added a boss which moves around horizontally. The next task is to make the game recognize that when level 1 is done it should go to level 2. Level 2 wasn't very hard to do once I got the game back working again. I had a little trouble with the planes interfering with the game, causing weird artifacts sometimes. This was due to the characters moving too far to the left of the screen. I learned a long time ago that if a character gets too far left, that happens. So I corrected it and it now works well.
The ship is now yellow, and the white enemy is now red. But I think I'm going to change the ship to red and have the red enemy be purple because I want to have a desert level with a yellow background. Which means the 4-digit yellow number (the high score) will have to change its color as well. I'll have to look for a longplay YouTube video on Xevious because I stink at playing it. I now just discovered that CTRL+arrow key right makes the cursor skip to the next word you typed if it wasn't there before. CTRL+arrow key left makes the cursor go back a word while typing this blog entry. How odd.