Career
He tied for 1st-4th places with Liviu-Dieter Nisipeanu, Vlastimil Babula and Zoltán Almási at the Krynica 1998 (zonal tournament). A four times qualifier for the FIDE World Championship finals (Las Vegas 1999, New Delhi 2000, Moscow 2001 and Tripoli 2004), at Delhi he beat Jonathan Speelman, Michał Krasenkow, and Alexander Beliavsky but lost in 4th round to Viswanathan Anand. He played for Poland in six Chess Olympiads.
In 1998, at third board in 33rd Chess Olympiad in Elista (+3−1=6);
In 2000, at third board in 34th Chess Olympiad in Istanbul (+3−1=6);
In 2002, at second board in 35th Chess Olympiad in Bled (+1−0=10);
In 2004, at first board in 36th Chess Olympiad in Calvià (+4−3=5);
In 2006, at second board in 37th Chess Olympiad in Turin (+1−2=5);
In 2012, at fifth board in 40th Chess Olympiad in Istanbul (+5−1=3).
Awarded the International Master title in 1996, and the Grandmaster title in 1999. In opening theory, Macieja has made contributions to the Classical Variation of the Nimzo Indian Defense.
After 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Qc2 c5 5.dxc5 0-0 6.a3 Bxc5 7.Nf3, Macieja popularized 7..b6. David Vigorito has called this line the "Macieja Variation" and considers it Black"s best try in the 4..c5 defense against 4.Qc2.