Built to Rule!
Released in 2003, Hasbro's Built to Rule is a line of building block sets that, when assembled, resemble toys from some of Hasbro's other toylines: G.I. Joe, Tonka, and Transformers. The building blocks are compatible with the Lego or Mega Blocks brands of building blocks.
The Transformers Built to Rule toyline consisted of an Armada line, which recieved a very wide public release, and a short-lived Energon line, which only had a limited, test market release in Cincinnati, Ohio. The entire line seemd to perform slowly, so it was dropped in 2004.
Some fans posit that had the Transformers series followed the lead of the G.I. Joe and Tonka sets, with a standard large-character/vehicle block set but include a "normal" figure, for example a Mini-Con both compatable with the normal Armada line but with a few BTR-style construction pegs (the Joe sets had normal Joe figures with newly-sculpted forearms that had BTR pegs on their gauntlets), it might have done a little better. But since the entire branch was cancelled after a year, it's hard to say so with any confidence.
Construction
There are some significant differences between the Aramda and Energon sets, though both are based on the same basic premise. Each Transformers kit is centered around a "Trans-Skeleton", a very simple humanoid body that folds up for vehicle mode without disassembly. From there, extra parts are added to the Trans-Skeleton for either mode.
For Armada, the Trans-Skeleton was a very broad, flat solid plate with thin, stick-like limbs attached to it. This led to very awkward-looking robot modes, especially at the smaller sizes. Each of these sets also came with an incredibly simplistic "Mini-Con" partner kit that did have a more dedicated "Powerlinx" connector than the standard construction pegs, though these are a bit too thin to be used as attachment points for regular Mini-Cons (they stay, sort of, but it's a very loose connection).
The structure of the Trans-Skeleton was changed for a pair of small sets originally intended to be the Mini-Cons Ramjet and Rollout for the Armada series; a much more solid skeleton with larger, blockier limbs. These two kits were never released, but were altered to become the Energon characters Skyblast and Inferno. The rest of the Energon Built To Rule kits followed this style of Trans-Skeleton, leading to much more solid and sturdy-looking robot modes.
