Suggestions for systeme
The following packages have something in common with the package systeme. The packages are ordered in decreasing similarity.
- witharrows: “Aligned” math environments with arrows for comments
 - eqnalign: Make eqnarray behave like align
 - eqnarray: More generalised equation arrays with numbering
 - cases: Numbered cases environment
 - subeqnarray: Equation array with sub numbering
 - odesandpdes: Optimizing workflow involving odes and pdes
 - spalign: Typeset matrices and arrays with spaces and semicolons as delimiters
 - lpform: Typesetting linear programming formulations and sets of equations
 - mathdots: Commands to produce dots in math that respect font size
 - pmat: Typeset partitioned matrices
 - kbordermatrix: LaTeX version of \bordermatrix
 - petri-nets: A set TeX/LaTeX packages for drawing Petri nets
 - tex-ewd: Macros to typeset calculational proofs and programs in Dijkstra's style
 - variations: Typeset tables of variations of functions
 - undertilde-gen: A simple macro for placing a tilde under a character
 - autoaligne: Align terms and members in math expressions
 - anti: Typeset an anti-particle in maths mode
 - mandel: Compute the Mandelbrot set
 - proofs: Macros for building proof trees
 - xlop: Calculates and displays arithmetic operations
 - calcfrac: Calculates the value of an expression containing fractions
 - youngtab: Typeset Young-Tableaux
 - minim-math: Extensive maths for LuaTeX
 - qed: Produce an “end-of-proof” mark
 - simplified-latex: A Simplified Introduction to LaTeX
 - polexpr: A parser for polynomial expressions
 - pdfmsym: PDF Math Symbols — various drawn mathematical symbols
 - tuple: Expandable operations for tuples of numbers
 - stretchy: Macros for creating stretchy TeX symbols
 - formlett: Letters to multiple recipients
 - expex: Linguistic examples and glosses, with reference capabilities