You can try my Crazy Dream series. The early ones are made long time ago and I noticed that at times they are not that well designed as they could be, though. I suggest playing Crazy Dream 3, 8 and 9, which are the games, I'm quite happy with.
If you like ancient and minimalistic BD games, then Dr. Watson's BD4, Don Pedro's BD5-11 and No One's series are must plays.
You find all those games on my site. Many of them are bug fixed versions.
If you think, those fan games are all far too easy, then try Matthias Steiner's Boulder Dash Plus series. And don't forget to provide us with a longplay video, in case you are able to finish those games.
I'm going to start with your Games first, I've downloaded the zipped file and can see there are numerous other Game Series you have made besides Crazy Dreams (WOOOHOOO!!!)
I'll post now and then to let you know how I'm getting along with them.
Also try RTA Dash's games! They are not too difficult and very fun!
And if I may make some advertising for my own games, you may also try RockFort. The game is downloadable here in this forum, news section, topic "RockFort 1 and 2". There is a version for BRemake and one for Gdash. The Gdash version of RockFort 2 will also come out soon. RockFort has five levels, and at least level 5 will surely be a challenge for you!
I've downloaded RockFort 1 & 2 already. I don't have Gdash or Bremake yet so didn't get a chance to have a peek, I'm leaning towards using Gdash because of the posts I have seen on the Forum, hopefully RockFort 2 will be out in that format by the time I get around to it
I also downloaded RTA Dash 01, after a quick peek at the first few Caves I must say I like the presentation and feel of it
Right now I'm playing Crazy Dream Dash and have to say I really like the Diagonal movement element. Well....I liked it more once I figured out it was there to use and I wasn't trapped in corners or enclosures