Well If its any help...I am working in very high detail with hundreds of instanced objects...The trick is to use them wisely...If you look closely at Rayman Origins they were very clever to have Short levels( layouts)
with repeated instances of objects including enemies /environment props etc...
Yes its definitely possible...I am working on a few right now and they work fine you just have to realize how its done..Use Props that are static and like lego blocks ..Here is a LOW REZ screen shot of one such game...My layouts are about 32048x1024 which is as big as I could be bothered...Then just make lots and lots of Varied Sprite sheets and if you need to have randomness just switch the static animation frame..This Game runs fine at 1920 x 1080 FULLSCREEN...on and offline...Sorry but you cant play it yet for Trademark reasons...
It has hundreds of Objects, Particle fx galore, full sound score and SFX lighting FX Web GL, Working HUDS & message systems,DAY & NIGHT TIME TRANSITIONS, You can even make Radiosity and specular mapping if you really felt like it...the works and runs smooth as a whistle,.
My advice is to start slow and simple...
OK get that...? START SIMPLE...then get better,...
I think and practice that it is far better to MAP OUT EVERYTHING THAT YOU WANT IN YOUR GAME ON PAPER FIRST..
MAking a Professional Game from Experience is a HUGE planning effort..
OK ITS ALL ABOUT PLANNING lol...
In order to make a game like Rayman You need to know exactly how to make games...how to make them look good, to animate, sync with SFX, cutscenes,layout transitions, menu's the works...
As for the level design,
It's all about instances if you ask me...
Make lots of prefabbed parts that interlock or overlapp seamlessly...
You can even make procedural levels that spawn as you go randomly but you do need to know your stuff for that...
Everything is possible ..just keep trying and READ THE MANUAL read all you can...PM me if you need specific help..:)
Like I Said..This Screenshot is LOW rez but is complete game shot....These levels are HUGE..with around 6 to 10 layers of Parallax PLUS THE MAIN LEVEL just like Rayman..(Have a real close look at Rayman( think sprites!!!) and you will see how they did it! very clever)..These levels I am making play fast, smooth and have so many Special effects you will die...CONSTRUCT 2 ROCKS!!!! GO HTML 5!!!
<img src="http://s14.postimage.org/91qt42l35/Yukio_test1.jpg" border="0" />