Sorry, Devil Island is the English translated name of the game shown in the video in the first post - E Mo Dao - it reuses level layouts and maps from Getsu Fuuma Den. The whip movement in E Mo Dao also replicates the limited sword range from Getsu Fuuma Den as well, which is why it is so limited.
Playing around some more with the full version of Castlevania DX and it is quite interesting - it replicates quite a bit of the usual Metroidvania elements, including ability updates like double jump and sliding, their are sub weapons that you can use and enemies drop equitable items like armors etc that increase your stats - but there doesn't seem to be experience or levelling up, you just increase your stats through equipping items. There are 12 bosses as well, and you have to find keys to open the doors to the first 11 of them (the 12th being the final boss), but you can do the bosses in any order as well as each key will open any boss door you use it on (you can only use a key once).
I'd love to see the story line translated as well - from what I have managed to make out, it's pretty standard stuff - the Devil Castle has appeared again and a Belmondo Family descendant is on hand - interestingly enough, it is set in 1917 as well, the same year as Bloodlines. It seems like the creators put quite a bit of effort into it. There's a couple of alternate versions of it as well that change the graphics and settings to tie it into other franchises, as is often the case with these pirate games.
EDIT: Doing a quick and rough translation of the opening using Google Translate and not only is it set in 1917 but it also seems to star John Morris... basically it goes: 1917, the Devil Castle has returned. Belmondo Family descendant John Morris embarks on a journey to wipe out/destroy[?] the Vampire...