My days with shoot'em-ups started and ended with my MSX. I never had a MSX2 so I stayed with good-old Zanac, the great Nemesis (father of all Gradius). There was also Knightmare, a different kind of shooter since you are a viking... but the idea is more or less the same (shoot! shoot! shoot! kill'em all!!!!!!).
But unfortunatly I forgot the name of the best shooter I have ever played in MSX!!!! I was unable to find it anywhere in the net (and believe me, I have tons of msx games... I'm a mothafuka leecher).
I can't even describe it well... It was a vertical shooter... There were this planets you have to go in no especial order... I believe you had to buy or upgrade weapons... I remember this special laser... oh how I liked shooting those aliens with my mothafuca big laser gun... life was so good back then...