Medieval mountaineer. There's at least two different kinds of Lego games - ones like Stack-It and World Builder that are sort of simulations of the Lego construction process, and ones like Spybot that are more based on Lego characters and situations.
This, like the similarly castle-themed Speed Chamber, is firmly in the second category: you're a green knight who's chosen to wear a full suit of armour to climb up the side of an enormous wall. And it's not as if it offers you any protection against the snakes, scorpions and falling boulders either...
Controls: Mouse or arrow keys to move climber, Space or mouse button to jump in current direction of travel.
Tips: As with many of these games, it's all about working out the patterns of where the rocks and animals are going to go - and if the "Easy" option is a piece of cake, then "Hard" really offers a bit more of a challenge.