Honestly bro, for a one man project this is fantastic!
The animations and voices are lovely. The concept and idea of an alien impregnating random earth bitches is actually quite humorous. The characters are well drawn. Actually quite a well made feature!
However for a actual flash game, it could use some real improvements...
The controls for the wasd stuff isnt very smooth, and you dont get to watch the sex animations for long because of your stamina running out. The actually gameplay itself is kinda tedious because there seems to be an element missing. But overall it works so im not complaining.
I would recommend you play the game angel girl or shinobi girl, where you have to get to strip your girl and use a combination of tapping left and right to progress the sex.
I do think it would great in the next game though to incorporate some rpg and fighting elements into the game. Like you could actually explore the town or city more freely from a map, before looking for your next victim to rape and impregnate. Imagine being able to actually transform into different creatures or monsters like in those tentacle hentai movies! How cool would it be to clone the girls from the dna you obtain, or abduct them, and cage them in a dungeon like area in your spaceship, with all kinds of kinky probing machines and devices! You should also have to fight certain characters like mini boss fights (Look up the hentai games fighting of ecstasy ,and the hentai versions of mugen [kuromaru, slime]) before you get to actually have your way with them!
Overall I think you did a lovely job here. I had fun playing and i am really looking forward to the next installment, where hopefully you'll be able to incorporate and combine some ideas from the games I've mentioned.