I'm pretty sure H.E.A.T. Viper was one of the last figures I bought, back in the day. I picked up a few figures from the '89 lineup and none from the next year, so he was probably one of the last. I don't remember playing with him much, just kind of posing him with all his gear.
All I remember of the H.E.A.T. Viper as a character is in the comics when Baroness has him shoot a barricaded door in an attempt to kill Snake-Eyes.
It didn't work.
Anyway, it seems like there are a million Halo Actionclix in similar poses but with different weapons. I know the one I listed above isn't the same, but it's pretty close. I removed the alien gun this miniature had and made H.E.A.T. Viper's cannon with a plastic coffee straw and green stuff. The backpack, hoses and ankle missiles are also green stuff.
I didn't try to put fins on his ankle bombs because I got better things to do than go blind trying that.