Tackling - Ever played Back-Breaker? You can never have the same tackle more than once because of the technology and graphics. You should have hard tackles and light tackles; hard tackles take longer to recover from?
Passing - Have dodgey balls thrown? Have better miss passes? Inside passes? Crash Balls?
Kicking - Like on Fifa, you have a gauge/meter of how hard you kick. Kicks dont always go the way you want - you shouldn't have the arrow like on rugby 08.
Bouncing Balls - Balls don't always bounce forwards, they sometimes bounce in different directions.
Scrum - Rotate and Intentional Dive?
BLOOD - Have blood substitutes; no one on Rugby 08 bled?
Players - Have signature moves? Like a side step or a shoulder barge.
Weather - Changes play; more dropped balls if wet? People slip over?
Destructive pitch - If there is a lot of play in one area, the pitch starts to turn into a muddy mess
TRAINING MODE- Use tackle pads? And sort out some drills and moves.
Actions - Make the backs line drift? Make sure that it's harder to run through players; in Rugby 08, there was a lot of one man running through/around everyone...
More inspiring line-outs- all you had to do in 08 was jump at the front and you'd steal most opposition ball.
Have a referee that doesn't see somethings?
ONLINE
Game Modes - Have a mode where you can change the rules? e.g. No offside or All passes must be forward? SLOW MOTION?
Scoring - Scoring would be easy on Rugby 08; use your backs line and draw the last man, then pass... Also, the scoring techniques; diving and placing (Special Moves for players? e.g. Chris Ashton, Swan Dive?
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CREATE - A better create mode, make your own team? Take a picture and have it was their face?
Hope this was helpful